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Improved generator and detector of millimeter waves for use in microwave spectroscopy

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■LIBRARY
B & BS COLLEGE OF TEXAS
IMPROVED GENERATOR AND DETECTOR OF MTTJ.TMETER WAVES
FOR USE IN MICROWAVE SPECTROSCOPY
A DISSERTATION
by
W esley E . T o lb e rg
OOP
S u b m itte d t o t h e G ra d u a te S c h o o l o f th e
A g r i c u l t u r a l and M e c h a n ic a l C o lle g e o f T e x a s i n
p a r t i a l f u l f i l l m e n t o f th e r e q u ir e m e n ts f o r t h e d e g r e e o f
DOCTOR OF PHILOSOPHY
A u g u st 1958
C h e m istry
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
UMI N u m b e r D P 1 6 5 2 4
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In the unlikely event that the author did not send a complete manuscript
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IMPROVED GENERATOR AND DEIECTDR OF MTT.T.TlfRTRR WAVES
FOR USE IN MICROWAVE SPECTROSCOPY
A DISSERTATION
W esley E . T o lb e r g
A pproved a s t o s t y l e a n d c o n t e n t ty s
O M -M
Is .
(C om m ittee Chairm an7
(Head o f t h e D ep artm en t^
A u g u st 1958
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
ACKKOWLEDQIENTS
I r e s p e c t f u l l y o f f e r t h e d e d i c a t io n o f n y d i s s e r t a t i o n t o : .
My p a r e n t s , whose s t e m r e s p e c t f o r s c h o la r s h ip h a s l e d
me h e r e .
D r. A l b e r t W. J a c h e , f o r h i s c u r i o s i t y f o r r e s e a r c h , w i l l i n g ­
n e s s t o e x p lo r e and f o r h i s e x c e l l e n t l e a d e r s h i p .
M r. W illia m H en d erso n , w hose m a g n if ic e n t s k i l l s , u n f la g g in g
i n t e r e s t an d g r e a t c a p a c ity f o r w o rk in g w ith and d e v e lo p in g new i d e a s
w e re o f p rim e im p o rta n c e t o t h i s w o rk .
Bae s u p p o r t o f t h e W elch F o u n d a tio n , a s w e l l a s th e i n t e r e s t ,
en co u ra g em en t, s u p p o r t and f r i e n d s h i p o f t h e men o f th e C h e m istry
D ep artm en t a r e g r a t e f u l l y acknow ledged.
t
\
I
300620
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ABSTRACT
R e l a t i v e l y few l a b o r a t o r i e s a r e eq u ip p ed to w ork i n th e m i l l i m e t e r
wave r e g i o n .
T h is i s i n p a r t due t o t h e f a c t t h a t t h e r e g io n h a s o n ly
r e c e n t l y b een made a c c e s s i b l e by t h e w o rk e rs a t Duke U n i v e r s i t y .
In
a d d i t i o n , th e e x p e r im e n ta l d i f f i c u l t i e s d is c o u r a g e some who m ig h t o th e rw is e
e n te r t h i s f i e l d .
M illim e te r w av es a r e p ro d u ced b y t h e g e n e r a tio n o f h a rm o n ic s o f a
k l y s t r o n o u tp u t and a r e d e t e c t e d by a c r y s t a l r e c t i f i e r .
A s tu d y o f
s e v e r a l o f th e p a ra m e te rs in v o lv e d , b a s e d on a s im p le m o d e l, h a s l e d t c
th e d ev elo p m en t o f com ponents w hich a r e c o n s id e r a b ly e a s i e r t o a sse m b le
-
and o p e r a t e , more s t a b l e , h av e w id e r b an d w id th , and h a v e l o n g e r o p e r­
a tin g l i f e .
New c a tw h is k e r - c o n ta in in g p r o b e s have b e e n d e s ig n e d f o r u s e b o th
i n h a rm o n ic g e n e r a to r s and i n d e t e c t o r s .
I t h a s been e s ta b lid ie d th a t
e x p o su re to t h e atm o sp h e re i s i n j u r i o u s t o p e rfo rm a n c e .
T h is i n j u r y can
be l a r g e l y p re v e n te d b y s to r a g e i n a vacuum d e s i c c a t o r when n o t i n u s e .
C r y s ta l t h i c k n e s s and d ia m e te r a r e n o t I m p o r ta n t, b u t t h e c o n d itio n o f
th e s u rfa c e i s .
The p e rfo rm a n c e o f seme d i f f e r e n t c r y s t a l m a t e r i a l s
h a s been e v a lu a te d .
A new d e t e c t o r b a se d on t h e r e s u l t s o f th e s e i n v e s t i ­
g a t i o n s h a s b een d e s ig n e d and b u i l t .
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
TABLE OF CONTENTS
I n tr o d u c tio n .
1
L i t e r a t u r e S u rv e y
4
P re se n t In v e s tig a tio n
7
E x p e rim e n ta l
I.
TT.
H I.
IV .
V.
- V I.
VH.
T y p ic a l V id eo M icrowave S p e c tr o m e te r
H arm onic G e n e r a to r and D e t e c t o r o f
K ing an d G ordy
I n i t i a l M o d if ic a tio n o f t h e D e t e c t o r
F i r s t H y p o th e s is : R e d e s ig n o f
R a d i a t i o n P ro b e s
Second H y p o th e s is : C r y s t a l D im en sio n s
an d t h e C o n d itio n o f t h e C r y s ta l
S u r fa c e
New R o t a t i o n a l L in e o f NO2
R e d e sig n e d D e te c to r
9
11
14
17
23
37
38
D is c u s s io n
43
Sumnary
46
A p p en d ix
49
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1
INTRODUCTION
M icrowave S p e c tro s c o p y i s c o n c e rn e d w ith t h e i n t e r a c t i o n o f m ic ro ­
wave r a d i a t i o n w ith r o t a t i n g , d i p o l a r , g a s e o u s m o le c u le s ,
B o ta tin g
m o le c u le s may i n t e r a c t w i t h r a d i a t i o n th ro u g h o u t a v e r y w ide ra n g e o f
th e e l e c tr o - m a g n e t i c s p e c tru m .
3h t h e i n f r a r e d , v i s i b l e , and u l t r a ­
v i o l e t r e g i o n s , t h e i n t e r a c t i o n s a r e c o m p lic a te d by th e f a c t t h a t t h i s
r a d i a t i o n may a l s o r a i s e t h e m o le c u le s i n t o e x c i t e d v i b r a t i o n a l and
e le c tro n ic s ta te s .
I n t h e m icrow ave r e g i o n , t h e q u a n ta o f e n e rg y a r e
s u f f i c i e n t l y e n e r g e t i c to c a u s e t r a n s i t i o n s b etw een r o t a t i o n a l s t a t e s
an d b etw een some r a t h e r low l y i n g v i b r a t i o n a l s t a t e s .
I n t h e m ain , th e
s p e c t r a o b s e rv e d a r e p u re r o t a t i o n a l s p e c t r a w h ich h a v e t h e v i r t u e o f
b e in g r e l a t i v e l y e a s y t o i n t e r p r e t m a th e m a tic a lly .
The d e v elo p m en t o f m icrow ave s p e c tro s c o p y came a b o u t a s a r e s u l t
o f r e s e a r c h on r a d a r d i r i n g W orld War H .
The f i r s t s p e c tr o m e te r s con­
s i s t e d o f com ponents ta k e n d i r e c t l y fro m s h o r t w ave r a d a r a p p a r a t u s .
B a r l y s u c c e s s f u l a p p l i c a t i o n s l e d t o th e d ev elo p m en t o f in s tr u m e n ta tio n
w h ich e x te n d e d t h e wave l e n g t h ra n g e i n t o r e g i o n s w h ere many m ore o b s e rv a ­
b l e s p e c t r a w ere t o b e fo u n d .
The ra n g e o f m icrow aves i s c o n v e n tio n a lly d e f in e d a s t h e r a d i a t i o n
o f th e e le c t r o - m a g n e t i c s p e c tru m h a v in g w a v e le n g th s o f 10 m e te r s t o 1
m illim e te r.
R o t a t i o n a l s p e c t r a o c c u r f a r more f r e q u e n t l y i n t h e s h o r t e r
wave r e g i o n s , and i t i s r a t h e r m ore c o n v e n ie n t to l i m i t m icrow ave sp ec­
tr o s c o p y t o th e w a v e le n g th s from a fe w c e n ti m e te r s t o one m i l l i m e t e r .
I t i s common p r a c t i c e t o u s e e i t h e r th e te rm w a v e le n g th o r fre q u e n c y
o f ra d ia tio n .
These a r e r e l a t e d i n t h a t t h e i r p r o d u c t i s t h e sp eed o f
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2
lig h t.
W avelength i s o f te n u se d a s a d e s c r i p t i v e te im w h ich f i t s th e
r a d i a t i o n i n t o i t s r e l a t i v e p la c e i n t h e e le c tr o m a g n e tic s p e c tru m .
F req u en cy i s a te rm u s e f u l i n ' o b ta in in g a p h y s ic a l p i c t u r e o f t h e i n t e r ­
a c t i o n s o f r a d i a t i o n w ith m o le c u le s .
Ble i n t e r a c t i o n in v o lv e s c o n v e rs io n
o f r a d i a n t e n e rg y t o m o le c u la r e n e rg y o f r o t a t i o n and th e e n e r g y , E , o f
t h e l i g h t wave e q u a ls h , P la n c k * s C o n s ta n t, tim e s i t s f r e q u e n c y .
G as m o le c u le s a r e g e n e r a l l y c o n s id e re d t o r o t a t e end—o v e r-e n d a t
c e r ta in fre q u e n c ie s .
T r a n s i ti o n s betw een c e r t a i n s t a t e s a r e p e r m itte d
a c c o r d in g to r u l e s d e r iv e d from quantum t h e o r y .
When t h e r a d i a t i o n f a l l i n g
on m o le c u le s o f t h e g a s i s o f a f r e q u e n c y j u s t e q u a l t o t h e d i f f e r e n c e i n
f re q u e n c y betw een a s t a t e i n w hich t h e m o le c u le s a r e r o t a t i n g and one to
w hich th e y can g o , t h e r a d i a t i o n i s a b s o rb e d .
B ie r e a r e many p e r m itte d
t r a n s i t i o n s w hose f re q u e n c y d i f f e r e n c e s c o rre s p o n d t o m icrow ave f r e q u e n c ie s .
The a b s o r p tio n f r e q u e n c ie s o f a p a r t i c u l a r m o le c u le a r e d e te rm in e d by
i t s g eo m etry and t h e m asses o f i t s c o n s t i t u e n t a to m s, and t h e r e f o r e th e
g eo m etry o f t h e m o le cu le may be com puted from a know ledge o f t h e f re q u e n ­
c i e s o f i t s r o t a t i o n a l s p e c t r a and t h e m asses o f t h e atom s in v o lv e d .
M o le c u le s now b e in g s tu d i e d i n t h i s l a b o r a t o r y a r e n i t r o g e n d io x id e
and oxygen d i f l u o r i d e .
O f t h e s e two compounds, t h e c a l c u l a t i o n s p r e ­
d i c t i n g t h e r o t a t i o n a l sp e c tru m o f OF^ w e re c a r r i e d o u t h e r e .
l a t e d f r e q u e n c i e s a r e l i s t e d in t h e a p p e n d ix .
H ie c a lc u ­
Bie p r e d i c t e d sp e c tru m had
i t s m ost u s e f u l l i n e s in t h e m i l l i m e t e r w ave r e g i o n .
I n s tr u m e n ta tio n f o r
t h i s r e g io n h a s b e e n d ev elo p ed o n ly r e c e n t l y and i s a v a i l a b l e i n few
la b o ra to rie s .
T h is l a b o r a t o r y i s one o f th e few .
The in s tr u m e n ta tio n r e q u ir e d f o r t h i s r e g io n in v o lv e s u n i t s f o r
g e n e r a tin g h arm o n ic s o f c e n tim e te r w aves and e x tre m e ly s e n s i t i v e r e c e i v e r s
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3
f o r d e t e c t i n g th em .
E a r l y a tte m p ts a t o b ta in in g th e p r o p e r r a d i a t i o n
w ith w hich t o s tu d y OF2 showed t h a t th e a v a i l a b l e eq u ip m en t c o u ld n o t
p ro v id e a d e q u a te am o u n ts a t a n y o f t h e n e c e s s a r y f r e q u e n c i e s .
R ep eated
a tte m p ts showed c o n v in c in g ly t h a t s u b s t a n t i a l im provem ent w as n e c e s s a r y
i n te c h n iq u e s f o r o b t a i n i n g f r e q u e n c i e s h ig h e r th a n 8 0 ,0 0 0 m e g a c y c le s.
C o n s e q u e n tly , t h i s d i s s e r t a t i o n i s c o n cern ed p r i m a r i l y w ith th e s tu d y
o f p a ra m e te rs g o v e rn in g th e g e n e r a tio n and d e t e c t i o n o f m i l l i m e t e r w a v e s,
d ev elo p m en t o f g e n e r a l l y u s e f u l g e n e r a t o r s and d e t e c t o r s , and a r e p o r t
on a r o t a t i o n a l l i n e o f
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4
LITERATURE SURVEY
T h ere a r e r e l a t i v e l y few p a p e r s p u b lis h e d on t h e in s t r u m e n t a t i o n
f o r t h e g e n e r a t i o n an d t h e d e t e c t i o n o f m i l l i m e t e r w av es f o r t h e p u rp o s e
o f m icrow ave s p e c tr o s c o p y .
I n t h e i r b o o k , "M icrow ave S p e c t r o s c o p y " , ^
Townes and Schawlow h av e c a r e f u l l y re v ie w e d t h e p u b lis h e d w o rk .
T h is
w as a l s o done by G ordy, S m ith , and T ram b aru lo i n t h e i r somewhat e a r l i e r
(2)
t e x t , ' 1 w h ich o n ly m en tio n ed t h e l a t e s t d e v e lo p m e n ts i n t h e i r l a b o r a t o r y
o f a f a r b e t t e r g e n e r a t o r and d e t e c t o r f o r t h e h i g h e r f r e q u e n c i e s .
T hese
w ere rev iew ed m ore f u l l y b y Townes.
A l i t e r a t u r e s e a r c h t o d a t e h a s r e v e a le d no f u r t h e r p u b lis h e d r e ­
s e a rc h on h a rm o n ic g e n e r a t o r s a n d d e t e c t o r s o f m i l l i m e t e r w a v e s.
The
ones d e v e lo p e d by G ordy h a v e b e e n u s e d e x t e n s iv e l y t o d e te rm in e m o le c u la r
p a r a m e te rs o f a num ber o f r e l a t i v e l y s im p le m o le c u le s .
The s m a ll num ber o f p a p e r s i n t h i s f i e l d i s t h e r e s u l t o f s e v e r a l
fa c to rs .
M icrow ave s p e c tr o s c o p y w as d e v e lo p e d a s an o f f s p r i n g o f r a d a r
an d i s s t i l l y o u n g .
Few s c i e n t i s t s a r e a c t i v e l y w o rk in g w ith v e r y h i g h
f re q u e n c y s p e c tr o s c o p y a n d , b e in g a r e c e n t d e v e lo p m e n t, i t i s s t i l l i n
i t s d i f f i c u l t s ta g e s .
The f r e q u e n c i e s a b o u t ifc ic h we a r e m o st co n cern ed a r e th o s e b e tw e e n
t h e f a r i n f r a r e d and t h e c e n t i m e t e r w av es o f th e w e l l - e s t a b l i s h e d p o r t i o n
o f t h e m icrow ave r e g i o n .
The l i m i t o f th e f a r i n f r a r e d i s d e te rm in e d by
t h e f a c t t h a t th e r a d i a t i o n s o u rc e d e v e lo p s e x tr e m e ly s m a ll e n e rg y a s
one a p p ro a c h e s t h e m icrow ave r e g i o n .
I n a d d i t i o n , th e o p t i c a l m ethods
n e ed ed g iv e s u b s t a n t i a l l y lo w e r r e s o l u t i o n th a n th o s e i n h e r e n t i n
m icrow ave te c h n iq u e s .
I t i s much m ore d e s i r a b l e t o c o v e r t h i s g a p i n
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5
e n e rg y w h ile p r e s e r v i n g , i f p o s s i b l e , t h e h ig h r e s o l u t i o n a d v a n ta g e s o f
t h e m icrow ave m ethod.
The l i m i t o f d i r e c t g e n e r a tio n o f m icrow aves w h ich a r e 6 mn. lo n g
o r l e s s i s r e a c h e d when t h e e l e c t r o n i c o s c i l l a t o r s g e n e r a tin g t h e w aves
c a n n o t be made s u f f i c i e n t l y s m a ll.
s i z e a s th e w ave th e y p r o d u c e .
They m u st be o f th e same o r d e r o f
As th e c a th o d e becom es s m a l le r , th e
c u r r e n t r e q u i r e d t o g iv e d e t e c t a b l e am o u n ts o f r a d i a t i o n becom es s u f ­
f i c i e n t l y d e n s e to d e s t r o y th e u n i t .
B ecau se d i r e c t g e n e r a tio n o f th e s e w av es w a s n o t p r a c t i c a l , a tte m p ts
w ere made t o g e n e r a te them a s h a rm o n ic s o f lo n g e r w a v e s .
C e n tim e te r
w aves w e re f e d i n t o a s e n s i t i v e c r y s t a l r e c e i v e r w h ic h , w hen s u f f i c i e n t l y
s a t u r a t e d w i t h c e n t i m e t e r w ave e n e r g y , r a d i a t e d h a rm o n ic s .
w e re 2 , 3 , 4 , . . . .
l/2 , l/3 , l/4 ,
The h arm o n ic s
th e f r e q u e n c y o f t h e f u n d a m e n ta l, and t h e r e f o r e w ere
t h e w a v e le n g th .
O nly t h e h a rm o n ic s w e r e p e r m itte d
to re a c h th e d e te c to r .
U n its g i v i n g e n e rg y fro m 5 t o 3 mm. w e re r e p o r t e d i n 194-9
(3)
, fro m
3 t o 2 mm. i n 1 9 5 1 ^ , t o .7 7 mm. i n 1 9 5 4 ^ , and t o .5 8 7 mm. i n 1 9 5 6 ^ .
T h e se r e s u l t s w e re o b ta in e d by v e r y c a r e f u l s e l e c t i o n o f c r y s t a l s and b y
v e r y c r i t i c a l tu n in g o f t h e a p p a r a tu s .
The u n i t s w h ich w e r e u s e d t o
o b s e rv e e n e rg y a t 2 mm. do n o t f u n c t i o n a t a l l w e l l betw een 4 an d 2 mm.
a n d , f o r a l l p r a c t i c a l p u r p o s e s , a r e r e g a rd e d a s b e in g u s e f u l o n ly a t
w a v e le n g th s ab o v e 4 mm. ^
.
The o b s e r v a tio n s a t s h o r t e r w a v e le n g th s r e ­
q u i r e e x tr e m e ly c a r e f u l e x p e r im e n ta l w o rk .
The g e n e r a t o r s and d e t e c t o r s u s e f u l down t o 4 can. o p e r a te by d o u b lin g ,
t r i p l i n g , q u a d r u p lin g , and so on t h e fu n d a m e n ta ls aro u n d 1 .2 cm. i n
le n g th .
The im pro v em en ts w h ic h p e r m itte d g r a d u a l l y i n c r e a s i n g e f f e c t i v e —
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6
n e s s o f o p e r a tio n show a d e f i n i t e p a t t e r n .
The e a r l i e r m o d els w ere
s m a lle r s c a l e -v e rsio n s o f t h e c e n tim e te r w ave a p p a r a t u s .
The more
s e n s i t i v e u n i t s w e re b u i l t w ith t h e d e t e c t i n g e le m e n t and th e c r y s t a l
i n s i d e t h e w a v e g u id e .
The u n i t s s e n s i t i v e a t even s h o r t e r w a v e le n g th s
in c o r p o r a te d f u r t h e r r e f in e m e n ts i n t h e same d i r e c t i o n .
I n th e s e ,
s m a lle r c r y s t a l s and d e t e c t i n g e le m e n ts w e re p la c e d i n s i d e t h e w av eg u id e.
The c o n t a c t p r e s s u r e b etw een th e c r y s t a l and t h e d e t e c t i n g e le m e n t w as
c a r e fu lly c o n tro lle d .
The a c c e s s h o l e s i n t o t h e w aveguide w e re made a s
s m a ll a s p r a c t i c a b l e to a v o id a t t e n u a t i o n o f t h e r a d i a t i o n .
In a d d itio n ,
w a v e le n g th s lo n g e r th a n 4- nm. w e re f i l t e r e d o u t . .
The r a d i a t i o n s e e n b y t h e d e t e c t o r c o n s is te d o f 4-th and h i g h e r
h a rm o n ic s o f t h e fu n d a m e n ta ls a ro u n d 1 .2 cm. i n l e n g t h .
The lo w e s t h a r ­
m o n ics a r e t h e m o st p o w e rfu l, and th e pow er d ro p s o f f r a p i d l y w ith, each
s u c c e e d in g m u l t i p l e .
P r o o f o f th e p r e s e n c e o f th e s e h arm o n ic s w a s b a se d
on a stu d y o f r o t a t i o n a l l i n e s p e c t r a o f t h e l i n e a r m o le c u le , c a rb o n
oxy s u l f i d e ^ .
A t f o u r t h and h ig h e r h a rm o n ic s o f 1 .2 3 cm. r a d i a t i o n , t h e
s p e c tru m o f t h i s m o le c u le c o n s i s t s o f a s e r i e s o f l i n e s -Hhich a r e a lm o s t
e x a c t h a rm o n ic s o f th e lo w e s t fre q u e n c y l i n e .
T h u s, t h e r e w as s e e n a one
to one c o rre s p o n d e n c e betw een th e num bers o f r o t a t i o n a l l i n e s o f t h e m ole­
c u le and t h e h a rm o n ic s o f e n e rg y d e t e c t a b l e i n t h e r a d i a t i c n .
As a r e s u l t o f t h e s e o b s e r v a tio n s , i t w as p o s s i b l e , a t l e a s t i n
p r i n c i p l e , t o o b t a i n r o t a t i o n a l l i n e s anyw here w i t h i n th e ra n g e fro m a b o u t
10 mm. t o .5 8 7 mm.
T h is r e p r e s e n t s th e v a s t fre q u e n c y ra n g e fro m 3 0 ,0 0 0
to 510 ,0 0 0 m e g a c y c le s .
As im p re s s iv e a n a cco m p lish m en t a s t h i s d ev elo p m en t
w a s, th e r e tu rn e d o u t t o be some e x tr e m e ly d i f f i c u l t e x p e r im e n ta l h a n d i­
caps.
T hese w i l l be d is c u s s e d i n t h e n e x t s e c t i o n .
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
7
PRESENT INVESTIGATION
The w ork t o b e d e s c r ib e d i n t h i s d i s s e r t a t i o n w as begun a s th e r e ­
s u l t o f some o b s e r v a tio n s made d u r in g e a r l y a tte m p ts t o u s e th e m i l l i m e t e r
wave g e n e r a t o r s and d e t e c t o r s o f King an d G ordy.
I t i s im p o r ta n t t o n o te
t h a t t h e s e u n i t s had b ee n u sed s u c c e s s f u l l y by o t h e r s , a lth o u g h o n ly w ith
g reat d iffic u lty .
Uie f i r s t o b s e r v a tio n made h e r e w as t h a t , o f th e two
d e t e c t o r s and two g e n e r a t o r s on h a n d , o n ly o n e , a g e n e r a t o r , w as f u n c t io n ­
a l.
The m a lfu n c tio n was a n e l e c t r i c a l s h o r t w h ic h o c c u r r e d when t h e
r a d i a t i o n p ro b e e i t h e r f a i l e d t o p a s s th ro u g h th e a c c e s s h o le i n t o th e
w av eg u id e o r h i t t h e w av eg u id e a lm o s t i m n e d ia te ly o n m aking c o n ta c t w ith
th e c r y s t a l .
The r e a s o n f o r th e m a lfu n c tio n w as c u m u la tiv e m ach in in g
e r r o r s t o t a l i n g so m eth in g l i k e .0 0 6 in c h e s .
T h is i l l u s t r a t e s v e r y sim p ly
t h e o r d e r o f a c c u ra c y in v o lv e d i n c o n s tr u c tio n o f th e s e u n i t s .
The d e t e c t o r h a v in g th e s m a lle r m e c h a n ic a l e r r o r and t h e f u n c t i o n a l
g e n e r a t o r w e re k e p t i n t h i s l a b o r a t o r y f o r f u r t h e r s tu d y .
w ere r e tu r n e d t o th e m a n u f a c tu re r f o r r e p a i r .
The o t h e r s
F u r t h e r s tu d y o f th e
d e t e c t o r l e d t o a s u b s t a n t i a l m o d i f i c a t io n w h ic h w as d e s c r ib e d by T o lb e r g ,
H en d erso n and J a c h e
tn \
.
I n t h i s , th e r a d i a t i o n p ro b e w as i n s u l a t e d fro m
t h e w aveg u id e by m eans o f a w a tc h je w e l .
The change w as a c c o m p lish e d so
t h a t th e i n t e r n a l c h a r a c t e r i s t i c s rem ain ed i d e n t i c a l w i t h a n u n m o d ifie d
d e t e c t o r b u t su c ce ed e d i n r e n d e r in g i t f u n c t i o n a l .
A d d it i o n a l o b s e r v a t i o n s w ere made i n t e s t i n g th e m o d ifie d d e t e c t o r .
E n erg y w as found a t a few f r e q u e n c i e s , an d a d e f i n i t e p a t t e r n o f r e s p o n s e
wa3 e s t a b l i s h e d . ( F ig . 2 . )
S y s te m a tic ch an g es o f c r y s t a l d e t e c t o r s ,
r a d i a t i o n p r o b e s , and t u n i n g p a r a m e te rs l e f t t h e p a t t e r n e s s e n t i a l l y un­
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
3
changed.
S p e c i a l p o l i s h i n g o f th e c r y s t a l s u r f a c e s in c r e a s e d a m p litu d e
o f re s p o n s e b u t g av e no m arked change i n f r e q u e n c y o f r e s p o n s e .
R esponse
f a d e d r a p i d l y and w as n o t v e r y p r e c i s e l y r e p r o d u c i b l e w i t h r e s p e c t to
f r e q u e n c i e s o f maximum r e s p o n s e .
T here w e re th r e e n a rro w f re q u e n c y ra n g e s
i n w h ic h u s e f u l r e s p o n s e w a s o b ta in e d and d id n o t f a d e a p p r e c i a b l y .
C om parison w as made w i t h t h e o t h e r g e n e r a to r and d e t e c t o r a f t e r th e y
had b een r e t u r n e d i n w o rk in g o r d e r .
T h e ir b e h a v io r w as o n ly s l i g h t l y
d i f f e r e n t fro m t h e s e t t e s t e d e a r l i e r w ith t h e e x c e p tio n t h a t t h e m o d if i­
c a t i o n i n s t a l l e d h e r e made t h e l a t t e r s u b s t a n t i a l l y e a s i e r t o u s e .
I t w as e a s y t o s e e t h a t a p p l i c a t i o n o f th e m ore p r e c i s e m e c h a n ic a l
te c h n iq u e s a v a i l a b l e h e r e w o u ld s u b s t a n t i a l l y re d u c e t h e d i f f i c u l t i e s i n
m a n ip u la tio n b u t w ould p r o b a b ly do l i t t l e t o f i l l i n t h e g a p s among t h e
s e v e ra l fre q u e n c ie s o f u s e f u l re sp o n se .
The r e s p o n s e p a t t e r n may be
com pared w ith th e a p p e a r a n c e o f l i n e s p e c t r a o f an ato m e m i t t i n g r a d i a t i o n .
The ty p e o f e n e rg y p a t t e r n d e s i r e d i s o n e w h ic h m ore n e a r l y re s e m b le s t h e
co n tin u u m o f b la c k body r a d i a t i o n w ith w h ich t o s tu d y a s n e e d e d th e r o ­
t a t i o n a l b e h a v io r o f a n y m o le c u le c h o s e n .
I t i s p o s s i b l e t o p r o v id e a
co n tin u u m o f c e n t i m e t e r w ave e n e rg y by a p p r o p r i a t e s e l e c t i o n o f e l e c t r o n i c
o s c i l l a t o r s , e a c h o f w h ich c o n t r i b u t e s s e v e r a l d i f f e r e n t f r e q u e n c y r a n g e s
o f o u tp u t.
I t s h o u ld , i n p r i n c i p l e , b e p o s s i b l e t o g e n e r a te a continuum
o f h a rm o n ic s fro m t h i s c e n t i m e t e r wave r a d i a t i o n .
A t t h e tim e t h i s w ork w as begun, m i l l i m e t e r w ave e n e rg y w as a v a i l a b l e
o v e r fe w , r e l a t i v e l y n a rro w f re q u e n c y r a n g e s .
The d e v e lo p m e n t o f m i l l i m e t e r
wave g e n e r a t o r s and d e t e c t o r s g iv in g th e d e s i r e d co n tin u u m o f e n e rg y ,
i n c r e a s e d s e n s i t i v i t y and s u b s t a n t i a l l y i n c r e a s e d e a s e o f m a n ip u la tio n i s
d e s c r ib e d i n d e t a i l i n t h e s e c t i o n t h a t f o llo w s .
R e p ro d u c e d with perm ission of th e copyright owner. Further reproduction prohibited without permission.
EXPERIMENTAL
I n t h i s l a b o r a t o r y , t h e b a s i c c e n ti m e te r wave s p e c tr o m e te r c o n s i s t s
o f a v id e o sy ste m .
Ih e sy stem f o r o b s e rv in g m i l l i m e t e r w av es i s made up
o f a c o m b in a tio n o f t h e b a s i c c e n t im e te r w ave s p e c tr o m e te r a lo n g w i t h a
h a rm o n ic g e n e r a t o r and d e t e c t o r .
I t w i l l be h e lp f u l t o d e s c rib e b r ie f ly
th e v id e o sy ste m and t o r e g a r d i t h e n c e f o r th sim p ly a s th e e x p e r im e n ta l
a p p a r a tu s on w hich t h e com ponents o f i n t e r e s t , t h e h arm o n ic g e n e r a t o r s
an d d e t e c t o r s , a r e b e in g d e v e lo p e d and t e s t e d .
I n t h i s s e c t i o n , th e d e s c r i p t i o n i s e s s e n t i a l l y a d e f i n i t i o n o f
te r m s w hich w i l l be u se d th r o u g h o u t.
The d is c u s s io n i s a resum e o f t h e
p r o c e d u r e s and m a n ip u la tio n o f e q u ip m e n t.
H ie p a r a g r a p h s on p e rfo rm a n c e
a r e t h e e v a l u a t i o n o f t h e com ponents f o r g e n e r a tin g an d d e t e c t i n g h a r ­
m o n ic s on w hich t h i s w ork w as b egun.
I.
•
T y p ic a l V ideo M icrow ave S p e c tro m e te r
The s im p l e s t a p p a r a tu s f o r o b s e rv in g th e a b s o r p ti o n o f m icrow ave
r a d i a t i o n i s a s p e c tr o m e te r w h ic h em ploys v id e o p r e s e n t a t i o n .
h a s b e en d e s c r ib e d b y G o r d y ^ .
T h is sy stem
The s p e c tro m e te r c o n s i s t s o f a k l y s t r o n ,
th e s o u r c e o f v a r i a b l e , m onochrom atic r a d i a t i o n , a c e l l c o n ta in in g t h e
g a s th ro u g h w h ic h t h e r a d i a t i o n t r a v e l s , a d e t e c t o r c o n v e r tin g r a d i a t i o n
t o an e l e c t r i c a l s i g n a l , and a n o s c il l o s c o p e w h ich p r e s e n t s a v i s i b l e
im ag e o f t h e e l e c t r i c a l s i g n a l .
I n p a r t i c u l a r , t h e k l y s t r o n s u s e d h e r e c o v ered t h e r e g io n fro m
18 t o 26 KMC. and a r e R ay th eo n 2K33B and QK306.
The w av eg u id e o f th e c e l l
i s c o in s i l v e r and d e f in e d K b an d t y Gordy w ith i n t e r n a l d im e n sio n s
a p p r o x im a te ly 4 .2 5 x 1 0 .5 mm. c r o s s s e c t i o n .
The d e t e c t o r i s a 1N26
Reproduced with perm ission of the copyright owner. Fu rther reproduction prohibited without permission.
10
c a r t r i d g e ty p e s i l i c o n c r y s t a l r e c t i f i e r .
The k l y s t r o n o u tp u t i s m o n ito re d
a t a l l tim e s try means o f a B eth e - h o le c o u p le r eq u ip p ed w i t h a n o th e r UJ26
d e te c to r.
A pproxim ate w a v e le n g th m easurem ents may b e made w i t h a d e Mom a y —
B o n a rd i c a v i t y w av em eter w hich i s a t t a c h e d t o t h e c o u p le r .
The o u tp u t o f
t h e k l y s t r o n m o n ito rin g d e t e c t o r i s s e e n on t h e m o n ito r s c o p e .
The m a j o r i t y o f t h e r a d i a t i o n i s d i r e c t e d th ro u g h th e c e l l to
t h e r a d i a t i o n d e t e c t o r , t h e o u tp u t o f w h ich i s seen on th e d e t e c t o r sco p e.
I f t h e s i g n a l i s s u f f i c i e n t l y s m a ll, i t i s som etim es a d v a n ta g e o u s t o a m p lify
i t w ith a d i f f e r e n t i a l a m p l i f i e r b e f o r e p r e s e n t a t i o n on t h e o s c il l o s c o p e .
Tn t h i s sy ste m , t h e k ly s tr o n o u tp u t i s m odulated w it h a sa w to o th
v o l t a g e so t h a t , i n s t e a d o f g e n e r a tin g a c o n tin u o u s ly m onochrom atic beam,
i t g e n e r a te s o n e w hich c o n t a i n s , on t h e a v e r a g e , a n a rro w band ^of fre q u e n ­
c ie s .
The k l y s t r o n may b e tu n e d o v e r a r e a s o n a b ly w id e band o f f r e ­
q u e n c ie s .
O nly a s m a ll p o r t i o n o f t h i s band i s s e e n a t a n y one tim e on
t h e sc o p e s in c e t h e w id th o f an a b s o r p t i o n l i n e i s a b o u t 0 .5 m eg acy cle.
F o r t h i s w id th t o b e a n a p p r e c ia b le f r a c t i o n o f th e fre q u e n c y ra n g e d i s ­
p la y e d on a 10 cm. s c r e e n , t h e ra n g e m ust be o f th e o r d e r o f 5 m eg acy cles
a t 2 0 ,0 0 0 m e g a c y c le s .
When t h e s p e c tr o m e te r i s s e t u p i n i t i a l l y , th e
band o f f r e q u e n c i e s shown on t h e sco p e i s c o n s id e r a b ly w id e r ■Qian t h i s .
I t i s th e c o n v e n ie n tly a v a i l a b l e e n e rg y i n a p a r t i c u l a r fre q u e n c y r a n g e .
The a d j u s t a b l e p a r a m e te rs o f t h e s p e c tr o m e te r a r e tu n e d s o t h a t t h e e n e rg y
i s m axim ized o v e r th e p a r t i c u l a r r a n g e .
When t h i s h a s b een d o n e , th e
e l e c t r o n i c p a ra m e te rs a r e a d ju s te d s o t h a t th e n a rro w fre q u e n c y ra n g e
need ed t o lo o k f o r l i n e s i s p r e s e n te d .
I t i s th e n p o s s i b l e to scan a c r o s s
t h e ra n g e a few m eg a cy c le s a t a tim e .
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
11
The ab o v e d e s c r i p t i o n i s a b r i e f o u t l i n e o f th e a p p a r a t u s and
t h e o p e r a tio n o f a v id e o s y ste m .
O th e r sy stem s in v o lv e a m p l i f i c a t i o n
te c h n iq u e s g i v i n g in c r e a s e d s e n s i t i v i t y , S ta r k m o d u la tio n a n d / o r c o n tin u ­
o u s s t r i p c h a r t re c o rd in g o f t h e a m p lif ie d d e t e c t o r s i g n a l .
The u s e o f
t h e v id e o sy ste m i s j u s t i f i e d by i t s s i m p l i c i t y an d t y t h e f a c t t h a t one
may o b s e rv e i n s t a n t a n e o u s l y o v e r a r a t h e r b ro ad f r e q u e n c y ra n g e th e r e s u l t s
o f e f f o r t s t o t u n e t h e s p e c tr o m e te r t o optimum c o n d i t i o n s .
The l a t t e r i s
e s p e c i a l l y im p o r ta n t i n t h e e v a l u a t i o n o f g e n e r a t o r s and d e t e c t o r s o f
h i g h e r h a rm o n ic s o f th e e n e rg y p ro v id e d by t h e k l y s t r o n .
I t i s su f­
f i c i e n t l y d i f f i c u l t t o o b s e rv e t h e h i g h e r h a rm o n ic s o f c e n t i m e t e r e a v e s
i n a v id e o sy ste m .
A d d itio n a l, r e f in e m e n ts made b y c o n v e r tin g t o o t h e r
s y ste m s may be made when s u f f i c i e n t l y good h arm o n ic e le m e n ts h av e been
d e v e lo p e d .
U .
Harm onic G e n e ra to r an d D e te c to r o f King and G ordy
T h e se com ponents w e re d is c u s s e d a id i l l u s t r a t e d b o th t y King
an d Gordy i n th e o r i g i na l p a p e r ^
and b y T o w n e s ^ .
The d e s c r i p t i o n t h a t
f o llo w s d e f i n e s th e v a r i o u s p a r t s and t h e i r f u n c t io n .
1.
C r y s t a l P o s i t i o n i n g S crew : T h is p a r t i s a d i f f e r e n t i a l screw on w h ich
th e
c r y s t a l i s m ounted.
down t o t h e
th e
W ith t h i s s c re w , t h e . c r y s t a l i s d r iv e n v e r y s lo w ly
p o i n t o f t h e c a t w h is k e r .
The
c r y s t a l and c a tw h is k e r co m p rise
s e n s in g d e v ic e w h ic h s e e s t h e r a d i a t i o n w i t h i n th e w a v e g u id e .
The screw i s d e s ig n e d t o h ave a t r a v e l o f .004- in c h p e r t u r n .
I t i s r i g i d l y a t t a c h e d t o t h e fra m e o f t h e d e t e c t o r o r o f t h e g e n e r a to r
and i d e a l l y h a s no m e c h a n ic a l p l a y w h ich w ould l e a d to e r r a t i c c h a n g e s I n
th e p o s i t i o n o f c o n t a c t o f t h e c a tw h is k e r p o i n t o n t h e c r y s t a l n o r o f
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
"*
"
^
12
§F TtEXjfe
c ry s ta l/c a tw h is k e r c o n ta c t p r e s s u re .
2.
Ih e S ilic o n C ry s ta l:
The c r y s t a l i s m ounted on a b r a s s p in -which i n
t u r n i s a t t a c h e d to th e f l a t f a c e o f a s m a ll c y l i n d e r o f b r a s s .
In th e
o p p o s ite f a c e o f t h e c y l i n d e r i s a d r i l l e d a n d ta p p e d h o le i n t o w h ic h •the
c o rre s p o n d in g m ale p a r t o f t h e d i f f e r e n t i a l screw f i t s .
F o r t h e g e n e r a t o r , t h e c i y s t a l i s 1 mm. (.0 4 0 " ) i n d ia m e te r .
The p i n i s a b o u t 3 / l 6 n lo n g and o f t h e same d ia m e te r a s t h e c r y s t a l .
The
c r y s t a l s a r e o f v a r i a b l e t h i c k n e s s an d r a n g e fro m l / 2 t o 1 mm. t h i c k .
The d e t e c t o r c r y s t a l s a r e 1 /4 mm. ( .0 1 0 ”) i n d ia m e te r and
m ounted on a p i n o f t h e same d ia m e te r .
The p in i s a t t a c h e d t o "the same
s o r t o f c y l i n d e r t h a t i s u s e d f o r g e n e r a to r c r y s t a l s .
C are m u st b e ta k e n t h a t th e c r y s t a l i s n o t i n a d v e r t e n t l y b ro k en
o f f b e c a u s e th e s o f t s o l d e r bond b etw een c r y s t a l and p i n i s g e n e r a l l y r a t h e r
w eak .
I t a p p e a rs t h a t , i n th e f a b r ic a tic n o f th e s e c r y s t a l s , an ir r e g u la r
p i e c e o f t h e s i l i c o n i s s o ld e r e d o n to a p i n w h ic h i s a t t h i s tim e much
l a r g e r th a n i t s f i n a l s i z e .
T h is c ru d e a s se m b ly i s f i n i s h e d by g r in d in g
t o s i z e , a n d t h e bond i s j u s t s tr o n g enough t o h o ld d u r in g v e r y c a r e f u l
g r in d in g a n d f i n a l p o l i s h i n g o f t h e c o n t a c t s u r f a c e .
3.
M ounting B lo c k :
The b lo c k , when s o ld e r e d t o t h e w a v e g u id e , s e r v e s a s
a sim p le p o s i t i o n i n g d e v ic e f o r t h e d i f f e r e n t i a l sc re w and th e c a tw h is k e r
p lu g .
4.
W aveguide:
The d e t e c t o r h a s a s in g l e
o r t s t r i p o f G band g u id e ,
1 x 2 mm. i n t e r n a l c r o s s s e c t i o n , f la n g e d on one en d and d r i l l e d th ro u g h
i t s s h o r t e s t d im e n s io n .
in s e rte d .
Through o n e o f t h e s e h o l e s t h e c a tw h is k e r i s
The c a tw h is k e r i s p la c e d so t h a t i t c r o s s e s th e g u id e , and
i t s p o i n t l i e s i n t h e p la n e o f th e o p p o s ite i n n e r f a c e o f th e g u id e w h ere
R e p ro d u c e d with perm ission of the copyright owner. Fu rther reproduction prohibited without permission.
13
i t m eets th e s i l i c o n c r y s t a l .
F ig u re 2 i l l u s t r a t e s t h i s .
The g e n e r a t o r r e q u i r e s two p ie c e s o f w av e g u id e , one K band and
one G b a n d .
They a r e s o ld e r e d t o g e t h e r a t r i g h t a n g l e s , t h e G band g u id e
a to p th e o t h e r .
p ro b e.
T hs g u id e s a r e d r i l l e d t o acconm odate t h e r a d i a t i o n
The c r y s t a l e n t e r s th ro u g h th e G b an d w h ile th e p ro b e t r a v e r s e s
from t h e K band g u id e th r o u g h th e G band and m eets th e c r y s t a l .
5.
R a d ia tio n P r o b e s :
The p r o b e s a r e b r a s s s tu d s on w h ich 2 m il t u n g s t e n
w ir e c a tw h is k e r s a r e s u i t a b l y m ounted.
c a tw h is k e r w ire i n t o ‘th e w a v e g u id e .
The d e t e c t o r p ro b e i n s e r t s o n ly
The g e n e r a t o r p ro b e i s d e s ig n e d so
t h a t a b r a s s s t u b e x te n d s i n t o th e K b a n d g u id e and t h e a tta c h e d p ie c e o f
t u n g s t e n p a s s e s on th ro u g h i n t o t h e G b an d g u id e .
The b r a s s s tu b s e n s e s
th e fu n d a m e n ta l r a d i a t i o n fro m t h e k l y s t r o n , and t h e tu n g s te n c a tw h is k e r
r a d i a t e s h a rm o n ic s down th e G band g u id e .
These p r o b e s a r e d i f f i c u l t to s e t u p .
The w ir e m ust b e s t r a i g h t
an d e x a c t l y c o a x i a l w ith t h e i n s u l a t o r p lu g i n w hich t h e b r a s s c a tw h is k e r
m o u n tin g s tu d i s h e l d .
The 2 m il w ir e e n t e r s t h e w av eg u id e th ro u g h a
h o l e w h ich i s a b o u t .0 1 3 " i n d ia m e te r .
A l l t h e com ponents w hich make up
t h e d e t e c t o r and t h e g e n e r a t o r m u st be v e r y n e a r l y c o a x i a l w i t h th e h o le s
i n t h e w a v e g u id e .
I f n o t , t h e w ir e c a n n o t be made to e n t e r t h e g u id e
w ith o u t e i t h e r b e n d in g o r P o r t i n g .
6.
End P lu n g e r s :
The en d p lu n g e r c o n s i s t s o f a p ie c e o f b r a s s w h ic h
f i t s i n s i d e o f and p lu g s w a v e g u id e .
The i n t e r n a l f a c e o f t h e p lu g i n t e r ­
c e p ts t h e r a d i a t i o n com ing th ro u g h th e w a v e g u id e fro m th e s o u r c e .
The
p o s i t i m s o f th e p lu g s a r e a d j u s t a b l e so t h a t o n e may o p tim iz e th e
s ta n d in g wave c o n d itio n f o r maximum c o n v e r s io n o f r a d i a t i o n to e l e c t r i c a l
e n e rg y .
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
u
H I.
I n i t i a l M o d if ic a tio n c f t h e D e te c to r
I t w as p o in te d o u t above 1 h a t th e c a tw h is k e r c ru st p a s s th ro u g h
t h e h o l e i n t h e w av eg u id e w a l l w ith o u t to u c h in g i t .
N e i th e r o f t h e two
d e t e c t o r s o n hand w ere m a n u fa c tu re d w ith s u f f i c i e n t l y s m a ll e r r o r t o
p e r m it t h i s .
I t w as n e c e s s a r y to move t h e h o le i n t h e w av eg u id e so t h a t
t h e c a tw h is k e r c o u ld e n t e r w ith o u t s h o r t i n g .
Moving th e h o le w a s done a s f e l l o w s :
The d r i l l e d and ta p p e d
h o l e i n t h e m o u n tin g b lo c k i n t o w hich th e c a tw h is k e r p lu g i s i n s e r t e d
d e te r m in e s th e p o i n t a t w h ic h t h e c a tw h is k e r w i l l e n t e r t h e w a v e g u id e .
T h e r e f o r e , a n y th in g c o a x i a l w ith t h i s h o le i s c o a x i a l w ith t h e c a tw h is k e r .
F o r t h i s r e a s o n , a s p e c i a l d r i l l g u id e w as c o n s tr u c t e d .
I t w as e s s e n t i a l ­
l y a c y l i n d e r o f b r a s s w h ich f i t t e d s n u g ly i n t o t h e b lo c k and w h ic h had
b o re d i n i t s c e n t e r a h o le t o accommodate a .0 4 4 " d r i l l .
w as d r i l l e d th r o u g h .
On t h e
3
The w av eg u id e
i d e -through w hich t h e c a tw h is k e r e n t e r s
w as i n s t a l l e d a w a sh e r h a v in g an o . d . o f .0 4 4 " , i . d . o f .0 1 2 ° , and
t h i c k n e s s o f .0 2 0 " .
On t h e o p p o s ite s id e o f th e g u id e a w a s h e r h a v in g
t h e same o . d . , same t h i c k n e s s and J318" i . d . w as i n s t a l l e d .
I t w as th o u g h t t h a t some fo rm o f i n s u l a t i o n o f th e c a tw h is k e r
fro m t h e m e ta l o f t h e w av eg u id e w ould be e x tre m e ly d e s i r a b l e .
To a c c o m p lish
t h i s , a f r i c t i o n p l a t e w a tc h je w e l w as i n s t a l l e d on to p o f t h e w a s h e r
th ro u g h w hich th e c a tw h is k e r e n t e r s .
The je w e l w as a s y n t h e t i c ru b y h a v in g
an o . d . o f .0 4 4 " and an i . c . o f .0 0 6 " .
The d e t e c t o r w as a sse m b le d w ith c a tw h is k e r and c r y s t a l i n p la c e
b u t n o t in c o n ta c t.
d id n o t s h o r t .
The c a tw h is k e r e n te r e d th e w av eg u id e an d , o f c o u r s e ,
S in c e th e i n t e r n a l f a c e s o f t h e w a s h e rs w e re c o p la n a r w ith
t h e i n t e r n a l f a c e s o f th e w a v e g u id e , e s s e n t i a l l y no change w as made w ith
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
15
r e s p e c t to t h e tr a n s m is s io n o f r a d i a t i o n th ro u g h t h e w a v e g u id e .
I t w as n o te d t h a t t h e r e w as c o n s id e r a b le v a r i a t i o n i n th e
p o s i t i o n o f t h e c i y s t a l w ith r e s p e c t to t h e c a tw h is k e r p o i n t d e p e n d in g
on s l i g h t ch an g es i n o r i e n t a t i o n - o f t h e d i f f e r e n t i a l screw a s i t w as con­
n e c te d t o t h e m o u n tin g b lo c k .
The ch an g es in v o lv e d w e re sim p ly ih e r o ­
t a t i o n o f th e e n t i r e sc rew assem b ly w ith r e s p e c t t o t h e b lo c k .
The
c r y s t a l a t tim e s w as b ro k e n o f f b e c a u se th e v a r i a t i o n ex ceed ed t h a t
a llo w a b le f o r a .0 1 0 ’* d ia m e te r c r y s t a l t o e n t e r a n .0 1 8 " h o le i n t h e
w a v e g u id e .
To e l i m i n a t e t h i s h a z a r d , i t w as fo u n d e x p e d ie n t t o d r i l l a
p a i r o f s i g h t h o l e s i n t o t h e m ounting b lo c k .
T hese h o l e s w e re aim ed
d i r e c t l y a t th e . c r y s t a l when i t w as i n a p o s i t i o n j u s t o u ts id e o f th e
w av e g u id e .
L ig h t c o u ld be fo c u s e d cn t h e c r y s t a l from o p p o s ite s i d e s .
Hie s h in y s u r f a c e o f t h e c r y s t a l r e f l e c t e d s u f f i c i e n t l i g h t t o p e r m it
d e te r m in a tio n o f i t s p o s i t i o n w ith r e s p e c t to th e h o le th ro u g h w hich i t
had t o e n t e r .
I t w as n o t s u f f i c i e n t t h a t t h e c r y s t a l m e re ly e n t e r t h e h o le
w ith o u t b e in g b ro k e n .
I t w as n e c e s s a r y a l s o t h a t t h e c r y s t a l e n t e r i n
such a way t h a t t h e p o i n t o f th e c a tw h is k e r to u c h e d t h e c r y s t a l .
W hether
th e y w ould make c o n t a c t c o u ld n o t be d e te rm in e d s im p ly by o b s e rv in g t h e
s i l h o u e t t e o f t h e tvro p a r t s .
The s i l h o u e t t e w as s e e n by lo o k in g th ro u g h
t h e w aveguide w ith th e a i d o f a j e w e l e r * s lo u p e (2 1 /2 x , 2 i n c h fo c u s ) „
T h is i s o f n e c e s s i t y a one d im e n s io n a l s ig h t i n g w i t h b o th th e c a tw h is k e r
and c r y s t a l i n s e r t e d i n t o t h e w a v e g u id e .
An im age o f t h e tw o p a r t s w as o b se rv e d r e f l e c t e d fro m e a c h
s id e o f t h e I n t e r n a l f a c e s o f th e w aveguide p a r a l l e l w i t h th e c a tw h is k e r .
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
L IB R A R Y
A & m G3 LLEGE 6 F TEXAS
16
From a t l e a s t one o f
t h e s e im ag es an d th e s i l h o u e t t e , i t w as
p o s s ib le
t o d e te rm in e w h e th e r
t h e c a tw h is k e r and c r y s t a l w ould make c o n t a c t .
If
th e y w e re n o t a l i g n e d p r o p e r l y , th e c r y s t a l c o u ld b e moved s l i g h t l y ty­
r o t a t i on i n p l a c e o f t h e d i f f e r e n t i a l screw a s s e m b ly .
P e rfo rm a n c e :
The g e n e r a t i o n and d e t e c t i o n o f 4-th and
h ig h e r
h a rm o n ic s o f
c e n tim e te r wave r a d i a t i o n i s i l l u s t r a t e d i n th e g r a p h i n F ig u r e 1 .
O v er
t h e f re q u e n c y ra n g e o f IS t o 26 EMC, i t w as e a s i l y s e e n t h a t i n o n ly
t h r e e n a rro w f r e q u e n c y r e g i o n s w as th e re * s u f f i c i e n t r a d i a t i o n a v a i l a b l e
w ith w hich t o o b s e rv e r o t a t i o n a l s p e c t r a .
In a d d i t i c n , th e o u t p u t o f
e n e rg y a p p e a r s t o be a p e r i o d i c f u n c t i o n w i t h a m p litu d e s r a n g in g fro m
z e r o t o v a r i o u s m o d e ra te v a l u e s .
The e n e rg y s h o u ld b e c o n tin u o u s ly a v a i l a ­
b l e and c e r t a i n l y o f s u f f i c i e n t a m p litu d e w ith w h ic h to o b s e rv e s p e c t r a .
F ig u re 1 shows two c u r v e s .
t h e u n i t s w e re f i r s t s e t u p .
One i s t h e e n e rg y o b s e rv a b le when
The seco n d i s t h a t s e e n a f t e r tw o h o u r s .
T he o iitp u t and d e t e c t i o n fa d e d s u b s t a n t i a l l y d u r in g t h i s t im e .
U n le s s
t h e e n e rg y b e in g u sed h ap p en ed t o b e i n t h e n e ig h b o rh o o d o f 26 KMC, no
f u r t h e r o b s e r v a tio n s c o u ld be made a f t e r an h o u r o r tw o .
i b i s b e h a v io r
seemed t o b e t y p i c a l a t l e a s t o f t h e p a r t i c u l a r g e n e r a t o r and d e t e c t o r
b e in g o b s e rv e d .
Changes o f c r y s t a l s and c a tw h is k e r s made no a p p r e c i a b l e
change i n t h e e n e rg y o b s e rv e d .
On c o n tin u e d s tu d y o f th e com ponents o f King and G ordy a s
m o d ifie d b y u s , s e v e r a l f a c t s w ere n o t e d .
The f i r s t o f th e s e w as t h a t
e n e rg y c o u ld n o t b e o b ta in e d on f i r s t c o n t a c t o f t h e c r y s t a l and c a tw h is k e r
o f th e d e te c to r .
I t a p p e a re d t o b e n e c e s s a r y t h a t th e c a tw h is k e r b e b e n t
i n p l a c e b y e x c e s s iv e c r y s t a l p r e s s u r e on th e c a tw h is k e r .
A f t e r th e
w h is k e r w as b e n t, e n e rg y c o u ld be o b ta in e d b y r e d u c in g t h e c r y s t a l p r e s s u r e .
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
17
On c o n tin u e d r e p e t i t i o n o f t h e s e a r c h f o r e n e rg y , i t w as n o te d t h a t l e s s
b en d in g w as r e q u i r e d .
The tu n a b le p a ra m e te rs o f th e s p e c tr o m e te r w e re
a d ju s te d to optimum c o n d i t i o n s e a c h tim e .
I n a d d i t i o n , o v e r t h e p e r io d o f w eek s r e q u ir e d f o r t h e t e s t s ,
th e a m p litu d e o f e n e rg y became g r a d u a l l y l e s s a t optim um .
T here seemed
a l s o t o be no ch an g e i n t h e f r e q u e n c ie s a t w h ich nwHmum re s p o n s e w as
o b ta i n e d .
T hese f a c t s l e d u s t o p ro p o se an a tte m p t to e x p la in them i n th e
hope t h a t s u b s t a n t i a l im provem ent o f p e rfo rm a n c e c o u ld be o b ta in e d .
IV .
F i r s t h y p o th e s is :
R e d e sig n o f R a d ia tio n P ro b e s
O b s e r v a tio n s on t h e p e rfo rm a n c e o f th e com ponents o f K ing and
G ordy le d u s to p ro p o s e a sim p le m odel o f t h e m i l l i m e t e r wave r a d i a t i o n
w hich w as s e t up and a n a ly z e d i n t h e f o llo w in g w ays
The r a d i a t i o n w as
c o n s id e re d to be a s ta n d in g wave w i t h i n th e w a v e g u id e .
The o r i g i n o f
t h e wave i s t h e g e n e r a t o r c a tw h is k e r w h ic h s ta n d s i n a n a n t i —node o r
maximum o f th e w av e.
I n o r d e r f o r t h e d e t e c t o r c a tw h is k e r t o see t h e
r a d i a t i o n , i t m u st a l s o b e a t o r n e a r a n o th e r maximum o f th e w a v e .
The e n d - p lu n g e r s may be a d ju s te d to o p tim iz e t h e s ta n d in g wave
c o n d itio n a s t h e f r e q u e n c y o f t h e wave i s ch an g ed .
The w ave alw ay s
o r i g i n a t e s a t th e wa-rironm i n w h ich th e g e n e r a t o r s t a n d s .
A change i n
fre q u e n c y s h i f t s t h e maximum away fro m t h e d e te c to r - c a tw h is k e r and a l s o
r e q u i r e s a n a d ju s tm e n t o f end p l u n g e r s .
As th e maximum s h i f t s away
fro m t h e d e t e c t o r c a tw h is k e r , t h e amount o f e n e r g y se e n b y t h e d e t e c t o r
d ro p s o f f .
F u r t h e r change o f t h e fre q u e n c y s h i f t s a new maximum i n t o th e
v i c i n i t y o f t h e p ro b e an d t h e e n e rg y s e e n by th e d e t e c t o r a l s o i n c r e a s e s .
R e p ro d u c e d with perm ission of the copyright owner. Further reproduction prohibited without permission.
18
T h is m odel w as c o n s i s t e n t w ith th e p a t t e r n o f e n e rg y sh o w n i n
F ig u r e 1 and w ith t h e f a c t t h a t th e d e t e c t o r p ro b e had t o be o e n t i n o r d e r
t o w ork*
E v id e n tly , t h e r e w a s a* node a t th e c a tw h is k e r , and th e b e n d in g
su c c e e d e d i n s h i f t i n g t h e c a tw h is k e r tow ard th e marimrtm o f t h e w a v e .
T h is
m ig h t n o t h av e been o b serv ed h ad t h e fre q u e n c y a t w h ic h t h e sy ste m w as
s e t up b e en su ch t h a t th e p ro b e w as i n a ma-g-im-nm o f t h e w av e.
The m odel
p ro v id e d no e x p la n a tio n f o r t h e f a d in g o f r e s p o n s e .
*
The m odel b a se d on t h e e n e rg y p a t t e r n and t h e need f o r a o e n t
p ro b e l e d u s t o d e s ig n an a n te n n a f o r t h e d e t e c t o r .
r e s u l t e d w as sim p ly a b e n t c a tw h is k e r .
The a n te n n a w h ich
The je w e l and w a sh e r p r e v io u s ly
i n s t a l l e d i n t h e m o d ifie d d e t e c t o r w e re removed to p e r m it th e b e n t w ir e
t o e n t e r t h e w a v e g u id e .
The p ro b e w as m ounted on a s tu b w hich s e rv e d to
f i l l th e h o le c r e a t e d by t h e re m o v a l o f t h e w a s h e r .
F ig u re 2 shows t h e
c r o s 3 s e c t io n o f t h i s a rra n g e m e n t.
New D e te c to r P r o b e ;
The a n te n n a c o n s is te d o f a s e m i - c i r c u l a r lo o p 1 /2 m .
<
in ra d iu s .
T h is lo o p w as e x p e c te d t o i n t e r s e c t a t l e a s t some o f th e
e n e rg y o f any 4-th harm o n ic o f t h e c e n tim e te r w ave r a d i a t i o n b e in g u s e d .
T h u s, i f an y 4-th h arm o n ic r a d i a t i o n w e re p r e s e n t i n t h e w a v e g u id e , t h i s
a n te n n a w as e x p e c te d t o s e e i t .
T e s ts o f t h e lo o p showed t h a t r a d i a t i o n
w as d e t e c t a b l e o v e r w id e r in c r e m e n ts o f t h e f re q u e n c y ra n g e .
On com pari­
son w ith t h e e n e rg y p a t t e r n o f F ig u r e 1 , i t w as seen t h a t e a c h maximum o f
t h e new p a t t e r n w as b ro a d e n e d .
E nergy w a s a l s o se e n a t more f r e q u e n c i e s
th a n b e f o r e .
New G e n e r a to r P r o b e :
I n v iew o f t h e s u c c e s s o f th e lo o p a n te n n a f o r th e
d e t e c t o r , a v e r y s i m i l a r a n te n n a w as d e s ig n e d f o r t h e K b an d p a r t o f t h e
g e n e r a t o r p ro b e .
T h is i s shown i n F ig u r e 2 .
The p e r i o d i c r e s p o n s e o f
v.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
19
t h e d e t e c t o r ev en w i t h t h e new p ro b e w as e x p e c te d b e c a u s e t h e d e t e c t o r
saw o n ly w h a t th e g e n e r a t o r c o u ld s e e .
T e s ts o f th e g e n e r a t o r e q u ip p e d
w ith t h e new p ro b e r e v e a le d an e n t i r e l y new p a t t e r n o f e n e rg y o u tp u t.
The o u tp u t o f th e d e t e c t o r w as c o n tin u o u s o v e r v e r y w id e p o r t i o n s o f th e
f re q u e n c y r a n g e .
The l a c k o f r e s p o n s e a t c e r t a i n f r e q u e n c ie s a p p e a re d
t o be th e f a u l t o f th e k l y s t r o n .
A n o th e r k l y s t r o n w as i n s t a l l e d and
e n e rg y w as s e e n w here t h e p r e v io u s one had b la c k e d o u t .
Shape and O r i e n t a t i o n o f t h e D e te c to r P ro b e s
S haping a 2 n i l tu n g s te n
w ir e i n t o a lo o p a n te n n a w as fo u n d t o b e a t e d i o u s and d e l i c a t e t a s k ,
ih e f i r s t lo o p u s e d w as a p a i n s t a k i n g l y —fa s h io n e d s e m i c i r c u l a r lo o p .
Sub­
s e q u e n t lo o p s w e re l e s s —r i g o r o u s l y f a s h io n e d b e c a u s e d e s i r e d s h a p e s f o r
t e s t i n g w ere e a s i e r to make th a n w as t h e sm o o th er c u r v e .
The s i z e o f th e
lo o p w as l i m i t e d by t h e s i z e o f t h e h o le th ro u g h w h ic h i t e n te r e d th e
w a v e g u id e .
C e r t a i n d i f f e r e n c e s w ere n o te d i n t h e o u tp u t o f e n e rg y a s
e a c h shape w as t r i e d .
As t h e r a d i u s o f th e lo o p w as re d u c e d , th e o u tp u t
p a t t e r n became more l i k e t h a t o f a s t r a i g h t w i r e .
w as a l s o re d u c e d , and t h e o u t p u t l o s t a m p litu d e .
The h e i g h t o f th e lo o p
A r e c t a n g u l a r lo o p w as
m ade, b u t s in c e t h e c o m e r s w ere ro u n d e d , i t w as a s good a s t h e sm o o th er
cu rv e.
T h is w as a l s o t r u e o f t h e v e e -s h a p e d lo o p .
I t w as c o n c lu d e d fro m t h i s t h a t any a n te n n a re se m b lin g th e s e
»
t h r e e s h a p e s w as s a t i s f a c t o r y a s lo n g a s i t w a s a t l e a s t 1 /2 mm. i n
d ia m e te r .
I t w as r e a d i l y fo u n d t h a t th e lo o p h ad t o b e o r ie n te d tow ard
th e g e n e ra to r.
R e p e a te d t e s t s showed t h a t th e b e s t a m p litu d e an d f r e ­
quency c o v e ra g e o f o u t p u t w e re o b ta in e d when t h e lo o p w as w i t h i n a b o u t
2 0 ° o f e ac h s id e o f a l i n e b etw een t h e d e t e c t o r and th e g e n e r a to r b u t n o t
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20
on t h e l i n e .
Shape and O r i e n t a t i o n o f th e G e n e r a to r P r o b e ;
The sh a p e o f t h i s p ro b e
w as a l s o s e m i c i r c u l a r b u t d i f f e r e d i n t h a t i t w as u n s y m m e tric a l.
i s shown i n F ig u r e 2 .
T h is
The d ia m e te r o f t h e h o l e th ro u g h w h ic h i t e n t e r s
t h e w a v e g u id e i s 5 .0 mm. and th e lo o p e x te n d s t h e f u l l d i a m e te r , h a v in g
b e e n a t t a c h e d t o a n edge o f th e p l a t e w h ich f i l l s th e 5 .0 mm. h o l e .
Two s y m m e tric a l p r o b e s w e re made.
h a v in g a s m a lle r r a d i u s .
b e s t.
1 .3 mm.
T hese w e re sm o o th er c u r v e s
I t w as r e a d i l y s e e n t h a t th e l a r g e p ro b e w as
The d ia m e te r o f t h e w ir e from w h ic h t h e s e p r o b e s w e re made w as
S m a lle r w ir e h a v in g a r a d i u s o f 0 . 8 mm. w as e a s i e r t o make i n t o
a p ro b e an d seemed t o w o rk a t l e a s t a s w e l l .
I n one t e s t , a s t r a i g h t 2 m il tu n g s te n w ir e w as u s e d a s b o th
K band an d G ban d p r o b e s .
The o u tp u t o f e n e rg y d id n o t d i f f e r a p p r e c i a b l y
fro m t h a t o f a l a r g e ( 1 .6 mm.) l i n e a r b r a s s p ro b e i n th e K b a n d .
Hie r e
a p p e a re d t o b e l e s s d i s t u r b a n c e o f t h e s ta n d in g wave p a t t e r n a s diown byre fle c tio n s .
I t w as d e c id e d t h a t w ir e h a v in g a d ia m e te r o f fro m . 8 t o 1
mm. w as s a t i s f a c t o r y .
T h e re w as no d i f f e r e n c e i n p e rfo rm a n c e o f i d e n t i c a l l y sh ap ed
p r o b e s made fro m s i l v e r , n i c k e l - s i l v e r o r b r a s s .
I t w as o f i n t e r e s t t o s tu d y t h e c a tw h is k e r e x te n d in g fro m th e
end o f th e K band p o r t i o n o f t h e g e n e r a t o r p r o b e .
w ir e w ith no sm all lo o p f o r f le x i n g w as t e s t e d .
A s t r a i g h t tu n g s t e n
A lth o u g h i t f u n c t io n e d ,
t h e p o i n t w as much to o r e a d i l y b lu n te d -, and i t a p p e a re d t o s l i d e o f f th e
c r y s t a l a s t h e p r e s s u r e w as in c r e a s e d s l i g h t l y .
A n o th e r c a tw h is k e r h a v in g th e same sh a p e and o r i e n t a t i o n a s a
s a t i s f a c t o r y d e t e c t o r p ro b e w as t e s t e d .
T h is c u rv e d w ir e p ro d u c e d v e r y
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21
l i t t l e e n e rg y a t 4-th h a rm o n ic s .
w as h i g h e r th a n f o u r t h h a rm o n ic .
I t w as p ro p o se d t h a t th e e n e rg y o b s e rv e d
T h is w as s u p p o rte d a t a l a t e r d a t e when
a s i m i l a r l y b e n t w ir e p ro d u c ed no o b s e r v a b le 4-th h arm o n ic a b s o r p tio n a t
m u l t i p l e s o f 24-, 315 MC, i n t h e r o t a t i o n a l s p e c tru m o f OCS.
O r d i n a r i l y , s t r a i g h t c a tw h is k e r s w e r e u se d f o r th e g e n e r a to r
p ro b e.
The p ro b e w as c o n s tr u c te d so t h a t t h e tu n g s te n w i r e had a s m a ll
f l e x i n g lo o p w h ich w a s p o s it i o n e d i n th e p la n e o f t h e w a v e g u id e w a l l
b etw een G an d K b a n d .
w as a t t e n u a t e d .
When th e lo o p w as i n th e G band g u id e , th e e n e rg y
When p la c e d i n th e K band g u id e , n o change i n o u tp u t o f
e n e rg y w as n o te d .
I t w as d e c id e d fro m t h e above f a c t s t h a t t h e i d e a l shape and
o r i e n t a t i o n o f t h e g e n e r a t o r c a tw h is k e r w as a s t r a i g h t p ro b e w h ich w as
e x a c t l y c e n te r e d and v e r t i c a l w ith r e s p e c t to t h e s h o r t s i d e s o f th e G
band g u id e .
O r i e n t a t i o n o f t h e G e n e r a to r C r y s t a l ?
The g e n e r a to r c r y s t a l c o n t a c t
s u r f a c e may b e a r b i t r a r i l y a d j u s t e d an y w here fro m above t h e u p p e r , i n n e r
s u r f a c e o f t h e w av eg u id e to a p o s i t i o n w e l l w i t h i n t h e w a v e g u id e .
The
c a tw h is k e r p o i n t may a l s o b e p o s iti o n e d t o make c o n t a c t i n c o rre s p o n d in g
o rie n ta tio n s .
T e s ts o f e n e r g y o u tp u t w ere made i n t h r e e p o s i t i o n s o f t h e
c ry s ta l.
T h e se w e r e :
1 , c r y s t a l s u r f a c e a b o v e ; 2 , c r y s t a l s u r f a c e b elo w ;
and 3 , c r y s t a l s u r f a c e c o p la n a r w i th t h e u p p e r i n n e r s u r f a c e o f th e wave­
g u id e .
The r e s u l t s showed t h a t t h e r e w a s o n ly one p o s i t i o n o f t h e c r y s t a l
s u r f a c e f o r w h ic h no a d v e r s e e f f e c t s o c c u r r e d .
W ith t h e c r y s t a l above th e
g u id e , e n e rg y w a s m ore o r l e s s u n ifo r m ly a t t e n u a t e d .
I f i t w e re i n s i d e
t h e g u id e , t h e l o n g e r w ave r a d i a t i o n w as c u t o f f d i a r p l y .
T h is e f f e c t
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22
seemed t o be p r o p o r t i o n a l t o t h e l e n g t h o f c r y s t a l p r o tr u d in g i n t o th e
g u id e .
B ie l a t t e r w as se e n t o be a r e a s o n a b le r e s u l t due to t h e f a c t
t h a t th e p r o t r u s i o n o f t h e c r y s t a l i n t o t h e g u id e m akes t h e ■waveguide
e f f e c t i v e l y s m a lle r .
The i d e a l p o s i t i o n o f t h e s u r f a c e o f t h e g e n e r a to r
c r y s t a l w as o b v io u s ly th e one i n w h ich i t w a s c o p la n a r w ith t h e i n n e r
s u r f a c e o f th e w av eg u id e.
O r i e n t a t i o n o f D e te c to r C r y s ta l ;
s itio n o f th e d e te c to r c r y s ta l.
S im ila r t e s t s w e re a p p lie d t o t h e po­
The r e s u l t s d i f f e r e d .
The o u tp u t o f
e n e rg y w as a p p r e c ia b ly a t t e n u a t e d when t h e c r y s t a l p r o tr u d e d i n t o t h e
g u id e .
I t a p p e a re d n o t to m a tt e r w h e th e r t h e c r y s t a l w ere ab o v e o r
c o p la n a r w ith t h e g u id e .
The p r a c t i c a l r e s u l t s o f t h e s e o b s e r v a tio n s on c r y s t a l p o s i t i o n
w ere a s f o ll o w s :
The d e t e c t o r and g e n e r a t o r c a tw h is k e rs m u st be sh a rp e n e d
(and th u s s h o rte n e d ) eac h tim e th e y a r e s e t u p .
m ust be i n i t s i d e a l p o s i t i o n .
The lo o p o f t h e d e t e c t o r
S in c e i t i s p o s s i b l e t o h a v e t h e d e t e c t o r
c r y s t a l above t h e g u id e , t h e c a tw h is k e r may b e lo n g and t h u s may a l s o be
sh a rp e n e d s e v e r a l tim e s b e f o r e i t i s to o s h o r t .
O ddly enough, th e g e n e r a t o r K band p ro b e d o es n o t h av e t o b e
a l l t h e w ay down i n t o th e g u id e .
The c r y s t a l m u st b e c o p la n a r w i t h th e
G band g u id e s u r f a c e , b u t t h e K band p ro b e w o rk s w e l l e v e n though o n ly
t h r e e f o u r t h s e x te n d s i n t o t h e g u id e .
The g e n e r a t o r p ro b e may, a s a
r e s u l t , a l s o b e sh a rp e n e d s e v e r a l tim e s b e f o r e i t becom es to o s h o r t .
C a tw h isk e r C o n s tr u c tio n :
The m ethod u se d h e r e f o r a t t a c h i n g tu n g s te n
w ir e t o th e a p p r o p r i a t e b r a s s m ounting s tu d in v o lv e d some v e r y d e l i c a t e
w o rk .
S in c e h e a t i n g o f tu n g s te n w i r e in a i r e m b r i t t l e s i t ,
s o ld e r in g te c h n iq u e s w as a t f i r s t a v o id e d .
th e u s e o f
T he f i r s t c a tw h is k e r s made
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23
h e r e w ere a sse m b le d by p in n in g t h e .0 0 2 ” w ir e i n t o a .0 0 6 ” c h am p ferred
h o le w i t h a ta p e r e d b r a s s p i n .
The h o le w a s a t l e a s t .6 ma. d e e p .
a r e a o f c o n t a c t betw een t h e t u n g s te n w ire and t h e b r a s s w a s s m a ll.
H ie
Con­
tin u e d t e s t s w i t h a p a r t i c u l a r c a tw h is k e r showed r a t h e r m arked d e c r e a s e
i n e n e rg y o u t p u t .
R ep e ated s h a rp e n in g wa3 r e q u i r e d , and e a c h e x p o s u re
t o t h e e l e c t r o p c l i s h i n g b a th a l s o e x p o se d t h e t u n g s t e n / b r a s s j u n c t i o n t o
t h e c o r r o s i v e s p ra y o f th e b a t h .
d is a s s e m b le d an d ex am in ed .
C o rro s io n w as o b v io u s .
A new p ro b e w as m ade,
a s e a r l i e r p ro b es.
w ere i d e n t i c a l .
When t h i s p ro b e f a i l e d t o w o rk , i t w as
i h i s o n e had h a l f a s much c o n t a c t a r e a
I t f a i l e d t o w o rk , ev en th o u g h a l l o t h e r p a r a m e te rs
The c o n t a c t a r e a was i n c r e a s e d and th e p r o b e f u n c tio n e d
p ro p e rly .
I t w as d e c id e d t h a t f u r t h e r i n c r e a s e o f c o n t a c t a r e a and e l i m i ­
n a t i o n o f th e c o r r o s i o n p ro b lem w ere n e c e s s a r y .
T u n g ste n
w ir e w as n i c k e l
p l a t e d an d s o ld e r e d i n p l a c e .
A p a i r o f p ro b e s h a v in g s o ld e r e d c o n n e c tio n s b etw een tu n g s te n
and b r a s s w as 'made and t e s t e d .
Not o n ly w ere th e y a p p r e c ia b ly more
e f f i c i e n t in - e n e rg y o u t p u t , th e y w ere a l s o a p p a r e n tly l e s s s u s c e p t i b l e to
c o rro s io n .
V.
I t w a s n e c e s s a r y to a v o id h e a t i n g t h e t u n g s t e n w i r e t o r e d n e s s .
Second Ifc rp o th e sis:
C r y s t a l D im en sio n s and t h e C o n d itio n o f t h e
C r y s ta l S u r fa c e
F o r t u i t o u s l y , m o st o f t h e wo rk an p r o b e s w as done d u r in g p e r i o d s
o f v e r y low h u m id ity on a s i n g l e s e t o f c r y s t a l s .
I t w as
o b s e rv e d r a t h e r
e a r l y t h a t f a d in g o f t h e e n e rg y o u t p u t o c c u r re d when f r e s h l y p o l is h e d
c r y s ta ls w e re u se d .
The f a d i n g o c c u rre d o v e r a p e r io d o f a few d a y s , b u t
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
24
t h e r e a f t e r no a p p r e c i a b l e d ro p i n e n e rg y -was s e e n .
A f t e r d e v e lo p m e n t o f m ethods f o r o b ta in in g 4 t h h a rm o n ic e n e rg y
c o n t i n o u s l y a c r o s s t h e f re q u e n c y r a n g e fro m 20 t o 26 KMC., i t became o f
s p e c i a l i n t e r e s t t o i n c r e a s e o u tp u t o f e n e r g y to i h e l e v e l r e q u i r e d f o r
c o n v e n ie n t o b s e r v a tio n o f s p e c t r a .
As a r e s u l t o f o u r o b s e r v a t i o n t h a t
f a d i n g o f e n e r g y o c c u r r e d a s a f u n c tio n o f tim e a f t e r p o l i s h i n g t h e c r y s t a l
s u r f a c e s , a s tu d y o f a l l p a r a m e te r s c o n c e rn in g t h e c r y s t a l s w as u n d e r ta k e n .
C r y s t a l D ia m e te rt
1 .0 mm., .5 0 im . and .2 5 ma. d ia m e te r c r y s t a l s w ere
com pared i n th e g e n e r a t o r .
S in c e t h e gens* a t o r w a s d r i l l e d f o r 1 mm.
c r y s t a l s , i t w as n e c e s s a r y t o s le e v e t h e s m a lle r c r y s t a l s so t h a t th e y
o c c u p ie d t h e sam e s p a c e .
I h e s u r f a c e s w e re n o t p o lis h e d f r e s h l y .
d i f f e r e n c e i n a m p litu d e o f e n e rg y w a s n o t e d .
No
C r y s ta l d ia m e te r a p p e a re d
t o h av e n o e f f e c t .
C r y s t a l T h ic k n e s s ;
A 1 .0 am . d ia m e te r g e n e r a t o r c r y s t a l h a v in g a t h i c k n e s s
o f .7 0 mm. w as s e l e c t e d f o r t e s t i n g .
w as d e te r m in e d .
.3 8 mm.
The o u tp u t o f t h e u n p o lis h e d c r y s t a l
S u c c e s s i v e l y , t h e th i c k n e s s w a s re d u c e d t o .5 7 , .5 0 , and
The f i r s t r e d u c t i o n i n t h i c k n e s s w as a c c o m p li shed b y g r in d i n g
w i t h a n A rk a n sa s h a rd s t o n e .
The s u r f a c e w as n o t p o l i s h e d .
O u tp u t i n ­
c r e a s e d by a f a c t o r o f tw o b u t w a s e r r a t i c i n t h a t r e p e a t e d t e s t s d id n o t
a lw a y s g iv e e n e r g y .
The c r y s t a l w as p o lis h e d on a b u f f in g w h e e l w i t h s t a i n l e s s s t e e l
ro u g e .
O u tp u t re m a in e d a t t h e h ig h l e v e l and w as v e r y c o n s i s t e n t i n r e ­
p e a te d t r i a l s .
I h e t h i c k n e s s w a s re d u c e d a g a in b y g r in d in g and p o l i s h i n g .
p u t w as j u s t a s l a r g e a n d s t i l l c o n s i s t e n t .
fad ed .
O ut­
A f t e r s e v e r a l d a y s , o u tp u t
I t a p p e a re d t h a t c r y s t a l / c a t w h i s k e r c o n t a c t p r e s s u r e had to b e
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
25
i n c r e a s e d s u f f i c i e n t l y t o g r in d th r o u g h a n i n s e n s i t i v e l a y e r o f th e c r y s t a l .
I t w as d e c id e d t h a t c r y s t a l e f f i c i e n c y c o u ld be d o u b le d b y
g r in d in g and p o l i s h i n g t h e s u r f a c e b u t t h a t t h i s im provem ent w as n o t
p e rm a n e n t.
S in c e t h e d e t e c t o r c r y s t a l
tbs
a lr e a d y q u i t e s m a ll ( .0 1 0 " ) i n
d ia m e te r , th e e f f e c t o f d e t e c t o r c r y s t a l d ia m e te r w as n o t s tu d i e d .
I t w as,
h o w ev er, r e l a t i v e l y c o n v e n ie n t t o o b s e rv e t h e e f f e c t o f t h i c k n e s s .
T here
w as no a p p r e c i a b l e e f f e c t i n t h e r a n g e o f t h i c k n e s s fro m 0 .0 7 mm. t o 0 .3 5
mn.
One c r y s t a l , much t h i n n e r t h a n 0 .0 7 mm. gave a n i n t e r e s t i n g r e s u l t .
The e n e r g y o s c i l l a t e d b etw een p o s i t i v e and n e g a tiv e r e c t i f i c a t i o n .
P o lis h e d s u r f a c e s seemed to b e im p o r ta n t i n d e t e c t o r c r y s t a l s
a l s o b u t d id n o t s t r o n g l y i n c r e a s e a m p litu d e o f o u t p u t .
The g r in d in g o f
th e c a tw h is k e r p o i n t a g a i n s t th e s u r f a c e o f a n aged c r y s t a l b lu n te d th e
c a tw h is k e r p o i n t t o t h e e x t e n t t h a t l e s s e n e r g y w as s e e n .
A l l t e s t s c o n c e rn in g c r y s t a l d im e n sio n s and s u r f a c e c o n d itio n
w e re made on s i l i c o n ta k e n fro m 1B26 d i o d e s .
T h e re a p p e a re d t o b e v e r y
l i t t l e d iffe re n c e i n th e e f fic ie n c y o f th e s e c r y s t a l s .
R a n d o m ly -se le c te d
d e t e c t o r an d g e n e r a t o r c r y s t a l s , w hen p r o p e r l y p o lis h e d , gave q u a l i t a t i v e l y
t h e same a m p litu d e o f e n e rg y o u t p u t .
fre q u e n c y s e n s i t i v i t y .
There w as n o e v id e n c e o f v a r y in g
I t m u st be n o te d t h a t t h e e n e rg y o u tp u t w as v e r y
s e n s i t i v e t o a d ju s tm e n t o f s e v e r a l o t h e r p a r a m e te r s .
C o n s e q u e n tly , c h a n g e s
i n o u tp u t o f th e o r d e r o f a few p e r c e n t c o u ld n o t b e r e g a rd e d a s s i g n i f i ­
c a n t.
I n te r c h a n g e o f e n d - p lu n g e r s , f o r e x a m p le , changed o u tp u t by
s e v e r a l p e r c e n t d e p e n d in g on f r e q u e n c y o f t h e r a d i a t i o n .
T h is happened
i n a m anner w h ic h w as n o t v e r y r e p r o d u c i b l e .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
26
The change t o w h ic h s i g n i f i c a n c e w as a tta c h e d had t o in v o lv e
an I n c r e a s e o r d e c r e a s e i n o u tp u t o f more th a n 25%.
t o be r e p r o d u c ib le i n r e p e a te d t e s t s .
Such a change had
As a r e s u l t , t h e e v a lu a t io n o f th e
v a r i o u s p a r t s w as a t t h i s p o i n t e s s e n t i a l l y c o m p le te b e c a u s e none o f t h e
p a r a m e te rs a v a i l a b l e f o r change appeared, to h a v e s u f f i c i e n t c a p a c i t y f o r
i n c r e a s i n g o u tp u t o f e n e r g y t o t h e e x t e n t r e q u i r e d f o r c o n v e n ie n t o b s e r ­
v a tio n o f r o ta tio n a l s p e c tr a .
T h is w as t r u e w ith one e x c e p tio n .
C ry s ta l
4
m a t e r i a l s o t h e r th a n t h e s i l i c o n ta k e n from 1N26 d io d e s w e re a v a i l a b l e
and h a d , i t w as th o u g h t, t h e p o t e n t i a l f o r s i g n i f i c a n t l y c h a n g in g t h e
e n e rg y o u tp u t.
Mew C r y s ta l M a t e r i a l s i
Mew ty p e s o f s i l i c o n s e m ic o n d u c to rs w e re t e s t e d
a lo n g w i t h some germ anium ta k e n fro m a 1M35 r e c t i f i e r .
The sam p les o f
s i l i c o n w e re o b ta in e d v i a p r i v a t e com m unication w i t h M r. Jo h n H a tc h e r o f
T exas I n s tr u m e n ts I n c .
c u t fro m a b a r .
T hese sam p les c o n s is t e d o f t h i n s l a b s o f s i l i c o n
I t w as n e c e s s a r y to s o l d e r s m a ll p ie c e s o f t h e s l a b s to
th e c r y s t a l m ounting b lo c k and t o g r in d them t o th e p r o p e r s i z e f o r u s e
a s d e t e c t o r and g e n e r a t o r c r y s t a l s .
S i l i c o n s e m ic o n d u c to r m ust f i r s t b e n i c k e l p l a t e d b e f o r e i t can
be s o ld e r e d .
The n i c k e l p l a t i n g w as done a c c o r d in g t o t h e method o f
(a\
T o rre y and W hitm erv
.
The s i l i c o n w as e tc h e d i n a 9 /1 m ix tu re o f 48% HF
and c o n c e n tr a te d HNO^ w h ich w as d i l u t e d a s r e q u ir e d by t h e p a r t i c u l a r
c r y s ta l m a te ria l.
Too s tr o n g a s o l u t i o n l e f t a d a r k b lu e s u r f a c e a r e a
w hich w ould n o t h o ld a p l a t e .
A u n ifo rm e t c h w as o b ta in e d o n ly a f t e r
d e g r e a s in g w ith l i g h t h y d ro c a rb o n s o lv e n t .
The p l a t i n g w as fo u n d to b e
m ost a d h e r e n t on a c r y s t a l on w h ic h t h e e tc h in g ' p ro c e e d e d s lo w ly an d gave
a u n ifo rm c o a t o f rnnail b u b b le s on t h e c r y s t a l s u r f a c e .
A t t h i s s ta g e o f
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27
th e e t c h i n g p r o c e s s , t h e r e a c t i o n "was s to p p e d b y r i n s i n g i n a s tr e a m o f
■water.
The c r y s t a l w as im m e d ia te ly c o n n e c te d t o t h e c a th o d e o f a 1 .5
v o l t b a tte r y -p o w e r e d p l a t i n g c e l l .
The anode w as a s h e e t o f n i c k e l .
The
b a th c o n ta in e d 75 gram s o f n i c k e l arnnoni nm s u l f a t e , 15 gram s each o f b o r i c
a c id an d ammonium s u l f a t e i n a l i t e r o f s o l u t i o n .
w ith a n 870 ohm r h e o s t a t .
film s .
C u r r e n t w as c o n t r o l l e d
A slo w p l a t i n g p r o c e s s g a v e t h e m ost a d h e r e n t
Time r e q u i r e d w as o f th e o r d e r o f f i v e m in u te s .
'
The p l a t e d s l a b w as f r a c t u r e d i n t o s m a ll p i e c e s , one o f w hich
w as s o f t s o ld e r e d o n to a 1 mm. d ia m e te r b r a s s w i r e .
The w ork c o n s is t e d
o f a r a t h e r i r r e g u l a r l y - s h a p e d p ie c e o f s i l i c o n a t t a c h e d t o a s h o r t , t h i n
w ire .
The n e x t s t e p w as t o g r in d t h e c r y s t a l down t o a c y l i n d e r h a v in g
th e same d ia m e te r a s t h e w i r e .
A diam ond l a p w a s u s e d .
The l a p w as a ls o
u se d to f a c e o f f t h e en d o f th e c r y s t a l p r i o r to p o l i s h i n g .
s i z e w as s u i t a b l e f o r u s e i n t h e g e n e r a t o r .
T ie 1 a n .
D e te c to r c r y s t a l s w ere made
b y c a r e f u l l y g r in d in g t h e c r y s t a l and t h e w i r e down to 1/4- mm. d ia m e te r .
The diam ond l a p c o u ld be u se d t o r e d u c e th e d ia m e te r t o 0 . 5 mm. b u t
f u r t h e r r e d u c tio n w as s u c c e s s f u l l y c a r r i e d o u t o n ly by m eans o f t h e u s e
o f an A rk a n sa s h a r d s t o n e .
I h i s tu rn e d o u t to be an e x tr e m e ly t e d io u s
p r o c e s s , b u t t h e r e s u l t s a s o u t l i n e d below w e re v e r y g o o d .
The t h r e e s i l i c o n c r y s t a l t y p e s w e re g iv e n a s f o ll o w s :
two N
ty p e c r y s t a l s , on e 0 .2 0 ohm cm” -*- r e s i s t i v i t y and t h e o t h e r 0 .6 ohm cm” -*-;
and one P ty p e c r y s t a l o f r e s i s t i v i t y 0 .2 0 ohm cm” -*-.
S ix c r y s ta ls f o r
u s e i n g e n e r a t o r and d e t e c t o r w e re made u p , t h r e e f o r t h e g e n e r a t o r and
th re e f o r th e d e te c to r .
I t w as d e c id e d t o t e s t t h e s e i n m atched p a i r s .
A l l p o s s i b l e c o m b in a tio n s o f t h e t h r e e d i f f e r e n t ty p e s w ould r e q u i r e t h r e e
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
28
tim e s th e num ber o f e x p e r im e n ts .
I t w as th o u g h t t h a t , by c o m p ariso n w i t h
a IN26 d e t e c t o r , an e x t r a o r d i n a r i l y good d e t e c t o r o r g e n e r a t o r w o u ld b e
r e v e a l e d w i t h o u t c h e c k in g a l l p o s s i b l e c o m b in a tio n s .
C r i t e r i o n o f G e n e r a to r P e rfo rm a n c e :
The o n ly m ethod by w h ic h i t w as
p o s s i b l e t o d e te r m in e w h e th e r a g e n e r a t o r
te ls
one i n c o n ju n c tio n w i t h a w o rk in g d e t e c t o r .
-
f u n c t io n i n g w a s t o o p e r a te
As a r e s u l t , i t w a s p o s s i b l e
t o know o n ly t h a t b o th w e re f u n c t i o n a l o r t h a t one o f t h e two o r b o th
w e re n o t f u n c t i o n a l , b u t n o know ledge o f w h ich o n e w as n o t f u n c t io n i n g
w as a v a i l a b l e .
A m ethod f o r d e te r m in in g w h e th e r o r n o t t h e g e n e r a t o r w as
p ro d u c in g 4 t h h a rm o n ic e n e r g y w as r e q u i r e d .
A c c o rd in g t o Townes ^
, a h arm o n ic g e n e r a t o r f u n c t i o n s b e c a u se
i t i s r e c e i v i n g m ore e n e r g y th a n i t can r e s p o n d to i n a l i n e a r m an n er.
The c r y s t a l d io d e w hen s u f f i c i e n t l y s a t u r a t e d w i t h fu n d a m e n ta l pow er fro m
t h e k l y s t r o n r a d i a t e s th e e x c e s s o v e r l i n e a r pow er a s h a rm o n ic s o f t h e
fu n d a m e n ta l.
T h is i s a sm a ll f r a c t i o n o f th e i n c i d e n t r a d i a t i o n .
Thus
i t seemed t h a t a m easure o f g e n e r a t o r h arm o n ic o u t p u t c o u ld be d e te rm in e d
fro m a m easu re o f t h e n o n l i n e a r i t y o f t h e g e n e r a t o r e l e c t r i c a l o u t p u t .
I t w as s t a t e d e a r l i e r t h a t "the r e c e p t i o n o f r a d i a t i o n fro m t h e
k l y s t r o n b y t h e g e n e r a t o r w as m o n ito re d .
o r d i n a r i l y q u i t e s y m m e tr ic a l.
The p a t t e r n o n t h e sco p e w as
D u rin g t e s t s o f t h e v a r i o u s p a r t s , t h e K
b an d end—p lu n g e r s w e re a d j u s t e d t o maximum d e t e c t o r o u t p u t .
The o u tp u t
w as fflATimnm when t h e m o n ito r sco p e p a t t e r n show ed, i n s t e a d o f a sym m etri­
c a l c u rv e , one w h ic h p o s s e s s e d a f l a t t e n e d maximum.
I t w as i n f e e t
p o s s i b l e t o tu n e t h e K b a n d end p lu n g e r s so t h a t t h e m o n ito r p a t t e r n w as
a t f i r s t s y m m e tr ic a l, t h e n f l a t t e n e d - o u t, t h e n f o l d e d o v e r .
On c o n tin u e d
t u n i n g , th e f o l d - o v e r d e c r e a s e d , th e c u rv e becam e f l a t t e n e d a t i t s
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
29
maxi nmm and th e n r e v e r t e d t o th e s y m m e tric a l sh a p e a g a in .
S im u lta n e o u s ly ,
th e d e t e c t o r o u tp u t w as s e e n t o i n c r e a s e t o a wayimim concom m itbant w i t h
maximum f o l d - o v e r .
I t d e c re a s e d t o z e r o a s t h e m o n ito r c u rv e became
s y m m e tric a l.
R ep eated t e s t s showed t h a t a g e n e r a t o r w ss f u n c t i o n a l i f and
o n ly i f t h e m o n ito r c u rv e w e re f o ld e d o v e r .
Hie a p p e a ra n c e o f th e f o l d -
o v e r c o n s t i t u t e d an in d e p e n d e n t t e s t o f w h e th e r o r n o t th e g e n e r a t o r w as
p u t t i n g o u t 4-th o r h i g h e r h arm o n ic e n e r g y .
W ith in s m a ll l i m i t s , th e d e g r e e o f f o l d - o v e r i s a p p ro x im a te ly
p r o p o r t i o n a l t o h arm o n ic o u t p u t,
when t h e f o l d —o v e r w as o b s e rv e d immedi­
a t e l y a f t e r a sse m b ly o f t h e g e n e r a t o r , i t w as u s u a lly e q u a l to o r g r e a t e r
th a n t h e v e r t i c a l a m p litu d e o f t h e e n e r g y .
T h is f o l d - o v e r o f p a t t e r n
fa d e d r a p i d l y t o a v a lu e a b o u t 4- o r 5% th e v e r t i c a l a m p litu d e . Any
/
p a t t e r n w h ich re se m b le d t h i s c o u ld be u sed t o e s tim a te h arm o n ic o u tp u t.
P erfo rm an ce o f New C r y s t a l M a te r i a l s ;
The t h r e e p a i r s o f s i l i c o n c r y s t a l s
w ere t e s t e d t o d e te rm in e b o th th e g e n e r a t o r o u tp u t and d e t e c t o r e f f i c i e n c y .
The g e n e r a t o r eq u ip p e d w i t h an N ty p e 0 . 2 ohm cm~~ r e s i s t i v i t y c r y s t a l g ave
a m o n ito r sc o p e p a t t e r n w i t h two a n d one—h a l f tim e s t h e a m p litu d e o f an
o r d in a r y 1526 c r y s t a l o u t p u t .
1526 c r y s t a l .
The d e t e c t o r o u tp u t w as se e n f i r s t w ith a
T h is w as fo llo w e d by a t e s t w ith a d e t e c t o r c r y s t a l made
fro m t h e same m a t e r i a l a s t h a t i n t h e g e n e r a t o r .
a t l e a s t d o u b le t h a t o f t h e o r d in a r y c r y s t a l s .
The d e t e c t o r o u tp u t w as
The new d e t e c t o r c r y s t a l
w as q u a l i t a t i v e l y s u b s t a n t i a l l y b e t t e r th a n t h e 1N26.
B o th N t y p e s , a lth o u g h d i f f e r i n g by a f a c t o r o f t h r e e i n
r e s i s t i v i t y , gave a f i n a l o u tp u t o f h arm o n ic e n e rg y w h ich w as a t l e a s t
tw ic e a s s tr o n g a s th e 1526 c r y s t a l s .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
30
The P ty p e c r y s t a l s f a i l e d t o p ro d u ce any s i g n a l -w h atso ev er.
Die P ty p e g e n e r a t o r g av e no h a rm o n ic s -which c o u ld b e s e e n b y a w o rk in g
N ty p e d e t e c t o r ,
D ie P ty p e d e t e c t o r w as checked a g a i n s t a w o rk in g N
ty p e g e n e r a to r and a l s o g av e no r e s p o n s e .
The Germanium C r y s t a l t
A cc o rd in g t o T o r r y ^ , germ anium i s c a p a b le o f
g iv in g odd h arm o n ic s i n a d d i t i o n t o e v e n o n es i n c c n tra sfc w i t h s i l i c o n
*
w h ich a p p e a r s t o g iv e m o st o f i t s r a d i a t i o n a s ev en m u l t i p l e s o f th e
fu n d a m e n ta l.
Townes e x p re s s e d th e o p in io n t h a t germ anium w o u ld be b e t t e r ,
a lth o u g h none w as a v a i l a b l e i n a fo rm s u i t a b l e f o r u s e a s a h arm o n ic
g e n e ra to r.
Germanium c r y s t a l f o r th e p r e s e n t t e s t s w as rem oved fro m a
1N35 d io d e .
s tu b .
T h is c o n s i s t s o f a s l a b ( c . a . 1mm. sq u a re ) s o ld e r e d to a
C o n ta c t f o r r e c t i f i c a t i o n i s made w ith a w ir e h a v in g a r a t h e r
b lu n t p o in t.
I n a d d i t i o n , t h e r e c t i f i e r i s s e a le d i n a ceram i c tu b e and
f i l l e d w ith a f l u i d w ax .
The s e a le d c a p s u le t y p e 1R35 c a n n o t b e conven­
i e n t l y com pared w ith t h e c a r t r i d g e 1H26 c r y s t a l s i n t h e i r o r d in a r y u s e .
The above f a c t s e x p l a i n why germ anium h a s n o t b e e n used^ a p p r e c i a b l y .
The germ anium an d i t s a s s o c i a t e d s tu b w ere c u t down t o a 1 m .
c y l i n d e r s u i t a b l e f o r u s e i n th e h a rm o n ic g e n e r a t o r .
The c r y s t a l w as
i n s t a l l e d i n t h e g e n e r a t o r and t e s t e d a g a i n s t a w o rk in g d e t e c t o r o f N
ty p e s i l i c o n .
R esponse a t s e v e r a l f r e q u e n c ie s w a s s t u d i e d .
The G band w av eg u id e a s d e f in e d t y Gordy c u t s o f f tr a n s m is s io n
a p p r e c ia b ly below 8 0 ,0 0 0 MC.
harm o n ic o f 2 0 ,0 0 0 MC.
T h is c o r re s p o n d s t o f r e q u e n c i e s b elo w 4 t h
I n a n e x p e rim e n t a t a b o u t 1 9 ,1 0 0 MC., t h e h a rm o n ic s
e m itte d t y N ty p e s i l i c o n f a i l e d t o p a s s th ro u g h th e s p e c tr o m e te r c e l l i n
am ounts s u f f i c i e n t t o s e a r c h f o r r o t a t i o n a l l i n e s .
I t w as a p p a re n t t h a t
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31
t h e 4 t h h a rm o n ic com ponent o f th e r a d i a t i o n w as b e in g a t t e n u a t e d .
At th e
same f r e q u e n c y , th e o u t p u t o f t h e germ anium m as s u f f i c i e n t t o e n a b le u s
to se a rc h f o r l i n e s .
P re su m ab ly th e 4 t h h a rm o n ic s a t 7 6 ,0 0 0 MG w e re s t i l l
b e in g a t t e n u a t e d , b u t s u f f i c i e n t h ig h e r h arm o n ic pow er w as a v a i l a b l e t o
show a s u b s t a n t i a l am ount o f e n e r g y .
Ih e tu n in g o f G band end—p lu n g e r s i n t h e germ anium e q u ip p e d
sy stem d i f f e r e d fro m t h a t o f t h e s i l i c o n i n t h a t b etw een e n e rg y maxima a s
o b ta in e d b y ch a n g in g an d p lu n g e r p o s i t i o n , t h e e n e rg y d id n o t a s u s u a l go
to z e ro .
Ih e p o s i t i o n o f end p lu n g e r s i s e x p e c te d t o b e d i f f e r e n t f o r
maximum r e c e p t i o n o f e v e n and odd h a rm o n ic s .
The odds s h o u ld be s e e n w hen
t h e end p l u n g e r p o s i t i o n i s in te r m e d ia te b etw een maxima due to e v e n h a r ­
m o n ics.
I t w as a p p a r e n t t h a t odd h arm o n ic s w e re p r e s e n t i n s u b s t a n t i a l
am ounts com pared w i t h t h e o u t p u t o f s i l i c o n .
I t w as th o u g h t d e s i r a b l e t o c o n f ir m th e p r e s e n c e o f su c h h a r ­
m onics b y o b s e rv in g r o t a t i o n a l s p e c t r a .
The l i n e s w e re expe c t e d t o a p p e a r
i n a l t e r n a t i n g i n t e n s i t i e s - ev en s tr o n g , odd w eak.
S p e c tr a o f OCS w e re
se e n a t m u l t i p l e s o f 2 4 , 315 MC. show ing t h e p r e s e n c e o f odd h a rm o n ic s .
P e rfo rm a n c e o f th e germ anium a t o t h e r f r e q u e n c i e s re s e m b le d t h a t
o f N ty p e s i l i c o n i n t o t a l o u tp u t o f e n e r g y .
I t s b e h a v io r w ith r e s p e c t
t o c o n t a c t p r e s s u r e i s t h e sa m e , and i t s l i f e i n t h e p ie s e n c e o f h umid
a i r i s v e i y much th e sam e.
P h y s i c a l l y , i t i s l e s s h a r d b u t j u s t as. b r i t t l e ,
m aking i t somewhat e a s i e r t o m achine*
H arm onic O u tp u t a s a F u n c tio n o f T im er
F a d in g o f t h e h arm o n ic e n e rg y
r e s u l t e d fro m two i d e n t i f i a b l e c a u s e s .
I n i t i a l f a d i n g o f t h e com po nents
o f K ing an d G ordy a p p e a re d n o t o c c u r w hen t h e new r a d i a t i o n p r o b e s w e re
used.
The new p r o b e s e v i d e n t l y p o s s e s s e d m e c h a n ic a l s t a b i l i t y n o t i n h e r e n t
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
32
i n th e s t r a i g h t p r o b e s .
G ra d u a l f a d i n g o f o u tp u t w as . c o r r e l a t e d w i t h
c r y s ta l s u rfa c e c o n d itio n .
A f r e s h l y - p o l i s h e d c r y s t a l gave o u tp u t
■which w as o f t e n tw e n ty tim e s t h a t o f an a g e d o n e .
I t w a s p ro p o s e d t h a t
a d s o r p t i o n o f w a t e r v a p o r o r some o t h e r v a r i a b l e c o n s t i t u e n t o f th e
a tm o sp h e re w as r e s p o n s i b l e f o r ' t h e g r a d u a l l o s s i n o u t p u t .
O u tp u t w e n t
n e a r l y t o z e r o w hen t h e c r y s t a l s u r f a c e w as o b s e rv e d to re sp o n d v e ry
s l u g g i s h l y d u r in g a sse m b ly o f t h e g e n e r a t o r .
i s moved s lo w ly down t o t h e c a tw h is k e r p o i n t .
In t h i s s te p , th e c r y s ta l
The m o n ito r sc o p e n o r m a lly
re sp o n d e d t h e i n s t a n t i n w h ic h t h e c o n t a c t w as m ade, an d t h e s y s te m r e ­
q u i r e d v e r y l i t t l e a d ju s tm e n t to i n c r e a s e th e s i g n a l t o a maximum v a l u e .
An ag ed c r y s t a l a p p e a re d t o g iv e a s m a ll s i g n a l some tim e a f t e r c o n t a c t
w as m ade.
The s i g n a l w as i n c r e a s e d s lo w ly by added p r e s s u r e o f c r y s t a l
a g a i n s t c a tw h is k e r .
T he ad d ed p r e s s u r e b lu n te d t h e c a tw h is k e r p o i n t .
As a r e s u l t , th e g e n e r a t o r r e s p o n s e p a t t e r n had no f o l d - o v e r an d no
h a rm o n ic s w e re d e t e c t e d .
To t e s t t h e p r o p o s a l t h a t an a d s o rb e d l a y e r o f g a s o n th e
c r y s t a l s u r f a c e w as r e s p o n s i b l e f o r t h i s b e h a v i o r , a g e n e r a t o r c r y s t a l
ag ed i n u s e w a s s t o r e d i n a vacuum d e s i c c a t o r f o r 12 h o u r s .
I t w a s ex­
p e c te d -th a t a n a p p r e c i a b l e f r a c t i o n o f t h e a d s o rb e d g a s c o u ld b e rem oved
i n t h i s w ay.
T h i s c r y s t a l w as r e i n s t a l l e d i n th e g e n e r a t o r , and t h e
r e s p o n s e b e h a v io r w as o b s e r v e d .
im p ro v em en t.
Vacuum tr e a tm e n t r e s u l t e d i n s u b s t a n t i a l
R esponse w a s im m ediate and n o t s l u g g i s h .
The d e g re e o f
f o l d - o v e r i n t h e g e n e r a t o r re s p o n s e p a t t e r n w a s an a l l , h arm o n ic o u tp u t
d e te c te d w as a b o u t h a l f t h a t o f a f r e s h ly - p o lis h e d c r y s t a l .
I t w as d ed u ced t h a t p a ri; o f t h e l o s s w a s i r r e v e r s i b l e .
t i n u e d e v a c u a tio n y i e l d e d no im p ro v em en t.
Con­
'hie s o f t s o l d e r bond p r e v e n te d
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
33
th e u s e o f h e a t to p ro m o te d e g a s s in g o f th e c r y s t a l .
D e te c to r c r y s t a l s b eh av ed d i f f e r e n t l y i n t h a t r e t u r n to im m e d ia te
f i r s t c o n t a c t r e s p o n s e w a s o b ta in e d on e v a c u a tio n .
T h is w a s a c c o m p lish e d
w i t h no l o s s i n e f f i c i e n c y o f d e t e c t i o n .
The d i f f e r e n c e i n th e b e h a v io r o f t h e g e n e r a to r and d e t e c t o r
c r y s ta ls w as c o rre la te d w ith th e d iffe re n c e i n le v e ls o f r a d ia te d en e rg y
i n w h ich e a c h o p e r a te d .
The d e t e c t o r c r y s t a l s e e s m ic ro w a tts o f e n e r g y .
The g e n e r a t o r r e c t i f i e s a s much a s 40 m i l l i w a t t s d i r e c t l y r a d i a t e d fro m
th e k l y s t r o n .
r
The i r r e v e r s i b l e p a r t o f t h e l o s s o f g e n e r a t o r o u tp u t w as
shown n o t t o b e a s p o t b u rn o u t a t t h e p o i n t o f c a tw h is k e r o o n ta c t b y m eans
o f r e p e a t e d t e s t s i n w h ic h s e v e r a l p a r t s o f t h e s u r f a c e w e re u s e d .
A
b u rn o u t c o u ld have b e e n c a u sed b y t h i s much e n e rg y .
A n o th e r r e a s o n f o r t h e d i f f e r e n c e w as so u g h t i n a n a n a l y s i s o f
th e e f f e c t o f d i s s i p a t i n g s e v e r a l m i l l i w a t t s o f e n e rg y on a s u r f a c e
w h ic h h a s ' a t l e a s t a n o n o m o le c u la r c o v e r in g o f a d s o rb e d w a te r v a p o r .
It
w as p ro p o se d t h a t t h e f o r c e s h o ld in g t h e m o le c u le s on t h e s u r f a c e w e re
c o n v e r te d t o c h e m ic a l b o n d s b e tw e e n atom s on o r n e a r t h e s u r f a c e and p a r t s
o f t h e w a t e r m o le c u le .
I t w as r e a s o n a b le t o suppose t h a t t h e e l e c t r i c a l
e n e rg y in v o lv e d w as c a p a b le o f c a u s in g su c h c h a n g e s .
The d e f i n i t i o n o f t h e c a u s e f o r t h e i r r e v e r s i b l e ch an g e i n th e
g e n e r a t o r c r y s t a l w as co n firm e d b y show ing t h a t t h e change d i d n o t o c c u r
w i t h o u t th e p r e s e n c e o f an a b s o rb e d f i l m .
A g e n e r a t o r an d d e t e c t o r w e re
s e t u p , t e s t e d , s t o r e d i n vacuum an d r e t e s t e d .
A f te r r e p e a t e d t e s t s i n
w h ic h t h e u n i t s w ere a lw a y s s to r e d i n vacuum betw een t e s t s , th e e n e r g y
o u t p u t w as u nchanged o v e r a p e r io d o f f o u r w e e k s .
The o p e r a t i n g tim e w as
e q u i v a l e n t t o t h r e e o r f o u r l i f e t i m e s o f c r y s t a l s ex p o sed c o n tin u o u s ly
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
34
to t h e a tm o sp h e re .
As a r e s u l t o f t h e s e o b s e r v a t io n s , t h e c o n c lu s io n w as made t h a t
g e n e r a to r s and d e t e c t o r s c o u ld be made p e rm a n e n tly s e n s i t i v e b y cons t r u c t i o n
o f e v a c u a b le u n i t s .
F a i l i n g t h i s , th e u s e f u l l i f e c o u ld b e e x te n d e d o v e r
lo n g p e r io d s o f tim e b y s to r a g e i n vacuum*
C a tw h is k e rs x The s tu d y o f th e s e h ig h ly s e n s i t i v e an d r a t h e r d e l i c a t e
'w
c r y s t a l d io d e s q u i t e n a t u r a l l y y i e l d e d some u s e f u l in f o r m s tic n c o n c e rn in g
c a tw h is k e rs s c rib e d .
The sh ap e and th e p o s i t i o n i n th e w a v eg u id e h a v e b een d e r
I n a d d i t i o n , c o n s t r u c t i o n o f a s a t i s f a c t o r y j u n c t i o n betw een t h e
c a tw h is k e r an d th e b r a s s m ounting s tu d w as o u t l i n e d b r ie f l y *
%
S e v e r a l t i m e s , r e f e r e n c e h a s b een made t o t h e b l u n t i n g o f t h e
c a tw h is k e r p o i n t on t h e c r y s t a l s u r f h c e .
I t w as o b s e rv e d t h a t th e
g r e a t e s t o u tp u t o f e n e rg y w as o b ta in e d when im m ed iate re s p o n s e o c c u rre d
a t f i r s t c o n t a c t b etw e e n th e sh a rp e n e d c a tw h is k e r and a f r e s h l y p r e p a r e d
c ry s ta l su rfa c e .
The c r y s t a l / c a t w h i s k e r c o n t a c t p r e s s u r e w as fo u n d t o b e
a d j u s t a b l e o v e r a v e r y s m a ll r a n g e .
When th e c r y s t a l s u r f a c e h ad d e t e r i ­
o r a t e d , th e ad d ed p r e s s u r e r e q u i r e d to p e n e t r a t e t h e i n s e n s i t i v e l a y e r
b lu n te d th e c a tw h is k e r .
The d ro p i n e n e rg y o b s e rv e d w a s c o r r e l a t e d w ith
b o th c r y s t a l i n e f f i c i e n c y and b lu n te d c a tw h is k e r s , b u t a b l u n t c a tw h is k e r
w orked o n ly v e r y p o o r ly on a good s u r f a c e .
When c r y s t a l p r e s s u r e a d ju s tm e n ts w e re c a r e f u l l y and s lo w ly done
i t w as p o s s i b l e t o o p tim iz e t h e o u tp u t o f e n e rg y i n a g iv e n f r e q u e n c y
ra n g e b y e i t h e r d e c r e a s in g o r i n c r e a s i n g p r e s s u r e on b o th g e n e r a t o r and
d e te c to r c o n ta c ts .
T h is o p e r a tio n c o u ld be p e rfo rm e d o n c e .
S h i f t i n g to
a n o th e r fre q u e n c y ra n g e r e q u i r e d r e a d ju s tm e n t o f p r e s s u r e s f o r optimum
o u tp u t o f e n e r g y .
As a r e s u l t , i t was n e c e s s a r y t o r e s h a r p e n c a tw h is k e r s
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35
f o r e a c h new f re q u e n c y r a n g e i n w h ich r o t a t i o n a l s p e c t r a w e r e b e in g
s tu d ie d .
I t w as o b s e rv e d , h o w ev er, t h a t t h e f r e q u e n c y ra n g e a v a i l a b l e
'
a t e a c h s e t t i n g w a s s u f f i c i e n t l y w id e t h a t i t w as p o s s i b l e i n p r i n c i p l e
to m a in ta in d e t e c t o r —g e n e r a t o r s e t s p e rm a n e n tly u s e f u l f o r a g iv e n r a n g e .
I t w as p ro p o se d t h a t t u n g s te n wi r e t h i n n e r t h a n .0 0 2 " w o u ld b e
more s e n s i t i v e to h i g h e r h a rm o n ic s .
Ho s m a lle r w i r e w a s a v a i l a b l e , b u t
a l a r g e r w ir e c o u ld be made s m a ll e r b y e l e c t r o p o l i s h i n g t h e e n t i r e l e n g t h
r a t h e r th a n j u s t th e p o i n t .
The p r e s e n c e o f h i g h e r h a rm o n ic e n e rg y w as
p ro v e d b y t h e o b s e r v a tio n o f t h e r o t a t i o n a l s p e c tru m o f OCS a t m u l t i p l e s
o f 2 4 ,3 1 5 MC.
The t e s t s f o r e f f e c t o f s m a lle r w i r e showed t h a t , a s t h e
w ir e became t h i n n e r , h a rm o n ic s w e re s e e n p r o g r e s s i v e l y m ore e a s i l y .
The
s e n s i t i v i t y t o a l l h a rm o n ic s w as a p p a r e n tly i n c r e a s e d , t h e h i g h e s t ob­
s e rv e d h a v in g been t h e 1 0 t h .
The w ir e w a s r e d u c e d i n d ia m e te r u n t i l i t w a s s l i g h t l y l e s s t h a n
.0 0 1 " .
The tu n g s te n w as n o t u n if o r m ly rem oved by t h e e l e c t r o l y s i s , and
c e r t a i n p l a c e s e l e c t r o l y s e d more r a p i d l y th a n o t h e r s .
w ir e w as e a s i l y f r a c t u r e d .
C o n s e q u e n tly , t h e
However, o th e r sa m p le s o f th e w i r e p o lis h e d
sm o o th ly an d rem ain ed s t r u c t u r a l l y so u n d .
A phenomenon o f i n t e r e s t w as
th e f o r m a tio n o f a b la c k c o a ti n g on t h e s u r f a c e o f t h e w i r e .
c o u r s e , n e c e s s a r y t o e l e c t r o l y s e s lo w ly .
I t w as, o f
When t h e p o l i s h i n g w as c o m p le te ,
i t w as found t h a t th e c o a t i n g c o u ld b e rem oved by a p p ly in g a v o l t a g e p u l s e
4 tim e s h i g h e r th a n t h a t u s e d f o r slow p o l i s h i n g .
w as v e r y s a t i s f a c t o r i l y s h in y .
The r e s u l t i n g s u r f a c e
I t h ad b e e n o b s e rv e d t h a t w i r e s c o v e re d
w i t h t h e b la c k c o a tin g w ere n o t s e n s i t i v e t o r a d i a t i o n .
T u n g s te n w i r e
h a v in g a d e n s e , s h in y b l a c k c o a tin g w as a l s o s e e n t o b e i n s e n s i t i v e .
w ir e had t o h a v e a m e t a l l i c sh e e n i n o r d e r t o f u n c t i o n .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
The
36
I t w as i n t e r e s t i n g t o n o te 1 h a t t h e u s e o f t h i n n e r tu n g s te n
s i r e gav e a n ad d ed a d v a n ta g e -
T he p o i n t w a s n o t a s r e a d i l y b l u n t e d .
P r e s s u r e a d ju s tm e n ts s e r e made s e v e r a l t im e s w it h o u t l o s s o f e n e r g y .
l i m i t w a s r e a c h e d w hen th e g e n e r a t o r w ir e b e n t .
T he
T h is r e s u l t e d i n l o s s o f
4-th h a rm o n ic e n e rg y a t l e a s t .
From t h e s e f a c t s , i t w as c o n c lu d e d t h a t d e t e c t o r s and g e n e r­
a t o r s h a v in g i n c r e a s e d s e n s i t i v i t y t o h i g h e r h a rm o n ic s and a w id e r r a n g e
o f c a tw h is k e r —c r y s t a l c o n t a c t p r e s s u r e c o u ld b e made w i t h t h e u s e o f 1
ant tu n g s te n w ire .
«
The i n c r e a s e d ra n g e o f p r e s s u r e a v a i l a b l e made i t
p o s s i b l e t o ch an g e f re q u e n c y r a n g e s w ith o u t r e s h a r p e n in g c a tw h is k e r s
q u i t e so o f t e n .
I h i s r e s u l t made p o s s i b l e , i n p r i n c i p l e a t l e a s t , th e
c o n s t r u c t i o n o f a sem i—p e rm a n e n t s e t o f d e t e c t o r s an d g e n e r a t o r s i n
w h ich th e e n e r g y c o u ld be o p tim iz e d a t w i l l 0
C r y s t a l N o is e :
N o is e g e n e r a te d a t t h e c r y s t a l w as a p p r o x im a te ly p r o ­
p o r t i o n a l to t h e e n e r g y f a l l i n g o n t h e d e t e c t o r .
how ever, much n o i s i e r th a n o t h e r s .
Some c r y s t a l s w e r e ,
T h is a p p e a re d t o b e r e l a t e d t o t h e
q u a l i t y o f t h e j u n c t i o n b etw een th e s i l i c o n a n d t h e b r a s s p i n .
A n o is e
t e s t o f v a lu e w a s d e v e lo p e d w hen i t w a s s e e n t h a t c r y s t a l s w h ic h f a i l e d
t o r e d u c e t h e z e r o e n e rg y n o i s e l e v e l o n f i r s t c o n t a c t w i t h t h e c a t ­
w h is k e r w ere t o o n o is y f o r u s e .
On re m o v a l fro m t h e d e te c to r? , t h e y w e re
u s u a l l y fo u n d t o be b ro k e n lo o s e fro m t h e p i n .
T h is t e s t p ro v e d o f v a lu e
i n d e te r m in in g w h e th e r o r n o t a c r y s t a l had. b een s u c c e s s f u l l y i n s t a l l e d .
O th e r conm ents r e g a r d i n g n o i s e a s a f u n c t io n o f e n e r g y and o f c o n t a c t
q u a l i t y h av e b een r e p o r t e d b y o t h e r s . ^
End P l u n g e r D e s ig n ;
S ta n d a rd end p lu n g e r s p ro v e d t o b e e x tr e m e ly to u c h y
an d d i f f i c u l t t o a d j u s t i n c e r t a i n f r e q u e n c y r a a g e s .
The e n d p lu n g e r s
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37
w ere s u f f i c i e n t l y e r r a t i c t h a t o b t a i n in g e n e rg y o f t e n d ep en d ed on a c h a n c e
a d ju s tm e n t.
p e rfo rm a n c e .
I t w as th o u g h t t h a t a p a r a b o l i c r e f l e c t o r m ig h t en h an ce t h e
One s u c h tra s made f o r t h e K b an d .
A th in re c ta n g u la r sh e e t
o f c o in s i l v e r tra s b e n t i n t o a p a r a b o l i c c y l i n d e r .
H e lo c u s o f th e f o c i
o f th e p a r a b o l i c s e c t i c n s tra s t h e s t r a i g h t l i n e o f t h e l i n e a r g e n e r ­
a to r p ro b e.
U n f o r tu n a te ly , su ch a f i x e d s u r f a c e i s t h e o r e t i c a l l y i d e a l
f o r o n ly one w a v e le n g th .
H e r e c t a n g l e w as made t o f i t s n u g ly i n t o t h e
K band g u id e o f t h e g e n e r a t o r .
T e s ts o f t h i s e n d p lu n g e r showed t h a t i t w as e v e ry w h e re b e t t e r
th a n a s ta n d a r d o n e .
I t w as t h o u g h t , how ever, t h a t t h e p a r a b o l i c shape
m ig h t have l e s s e f f e c t 1han t h e r e f l e c t i n g s u r f a c e w h ich f i t t h e wave
g u id e s n u g ly .
in g :
T e s ts o f a p l a n a r s n u g l y - f i t t e d p lu n g e r diaw ed th e f o llo w ­
F o r f r e q u e n c ie s above 24 EMC, a s ta n d a rd p lu n g e r a t t h e k l y s t r o n
end o f t h e K band and a f l a t r e f l e c t o r a t t h e g e n e r a t o r end w e re s u b s ta n tia lly b e tte r.
v e n ie n t m anner.
A bout 25% m ere e n e rg y w a s o b ta in e d i n a more con­
Below 24. KMC, f l a t r e f l e c t o r s w e re r e q u i r e d i n b o th
p o s itio n s .
F o r t h e G b a n d , th e s ta n d a r d end p lu n g e r s w e re f l a t r e f l e c t o r s , ,
Some im provem ent w as o b ta in e d b y f a c i n g o f f t h e r e f l e c t i n g s u r f a c e s .
V I.
New R o t a t i o n a l L in e o f NO2
The n ew ly d e r e lo p e d g e n e r a to r and d e t e c t o r w ere o o n b in e d w ith
a v id e o s p e c tro m e te r and u se d i n s e a r c h in g f o r a l i n e o f NO2 n e a r 1 2 5 ,0 0 0
MC.
The p o s i t i o n o f t h e l i n e w as p r e d i c t e d i n c a l c u l a t i o n s c a r r i e d o u t
by D r. G eorge SLrd o f th e R ic e I n s t i t u t e .
The s e a r c h f o r t h i s l i n e w as
co n d u c ted h e re w i t h t h e c o o p e r a tio n o f D r. B i r d ..
The r a d i a t i o n r e q u i r e d f o r f i n d i n g t h e l i n e w a s t h e s i x t h
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
38
h arm o n ic o f 2 1 .4 KMC-
-he s i g n a l o b s e rv e d a s e n e r g y c o n s is te d o f 4 th
p in s h ig h e r h a rm o n ic s, a n d , -when t h e l i n e w as f o u n d , i t s f re q u e n c y w as
known to b e o n e o f t h e s e v e r a l p o s s i b l e h a rm o n ic s o f t h e fu n d a m e n ta l.
T h a t t h e l i n e w as a t 6 th h arm o n ic o f 2 1 .4 KMC, w as i n f e r r e d b y
b e h a v io r o f t h e a m p litu d e o f t h e l i n e i n c o m p a riso n w i t h th e a m p litu d e
o f th e e n e r g y .
Odd h arm o n ic s w e re n o t c o n s id e re d l i k e l y t o b e r e s p o n s i­
b l e f o r t h e i n t e n s i t y o f a b s o r p tio n o b s e rv e d .
The tim in g o f e n e rg y from
maximum t o minimum, diowed t h a t th e l i n e w a s o f maximum a m p litu d e w hen
e n e rg y w as n o t a maximum.
By v i r t u e o f t h e s ta n d in g wave p a t t e r n con­
s i s t i n g o f a num ber o f h a rm o n ic s , one can show t h a t 4 t h , 8 t h an d so on
h arm o n ic s a r e maximum a t d i f f e r e n t tu n in g a d ju s tm e n ts fro m t h e
o f 6 t h , 1 0 th an d so o n .
mrm
S in c e th e m a j o r i t y o f e n e r g y i s 4 th h arm o n ic ,
t h e t o t a l e n e rg y w i l l b e maximum when 4 t h i s maxi mum.
T h u s, t h e l i n e
w as i n f e r r e d t o be e i t h e r 6 t h o r 1 0 th h a rm o n ic , and i t was n o t l i k e l y
t o b e 1 0 th .
The l i n e w a s p r e d i c t e d to b e n e a r 1 2 8 ,0 0 0 MC. and i t w as
fo u n d a t 1 2 8 ,2 2 1 .8 8 MC.
The f re q u e n c y o f t h e fu n d a m e n ta l w a s m easured
vfqv
b y means o f a f re q u e n c y s ta n d a rd good t o a t l e a s t 0 . 1 MC.
.
-
The c e l l u sed f o r t h i s d e te r m in a tio n w a s 2 m e te r s lo n g and had
th e i n t e r n a l d im e n sio n s o f K bandth ro u g h a ty p e P a m p l i f i e r .
V II.
The h arm o n ic o u tp u t w as a m p lif ie d
The p r e s s u r e o f SO2 g a s w as 45 microns<>
R ed esig n ed D e te c to r
The d e v elo p m e n ts th u s f a r le d u s t o b e l i e v e t h a t a new d e ­
t e c t o r and p o s s i b l y a new g e n e r a to r c o u ld b e d e s ig n e d t o h a v e some
r a t h e r s u p e rio r p r o p e r tie s .
The o n ly a v a i l a b l e u n i t s w ere e v i d e n t l y
made w ith c e r t a i n a s s u m p tio n s i n m ind.
I t w as a p p a r e n t t h a t c o n c e r te d
e f f o r t had b e e n made t o c o n s t r u c t t h e s y s te m so t h a t t h e r e w e r e th e
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39
l e a s t p o s s i b l e num ber and s m a l l e s t s i z e o f d i s c o n t i n u i t i e s i n th e G
band w av eg u id e p o r t i o n s o f t h e d e t e c t o r and g e n e r a t o r .
T h e re w as a l s o
r e a s o n t o b e l i e v e t h a t t h e c r y s t a l - c a t w h i s k e r r e c e i v e r had to b e i n s i d e
th e w a v e g u id e .
The c r y s t a l - c a t w h i s k e r c o n t a c t p r e s s u r e h ad t o b e co n ­
t r o l l a b l e w i t h i n r a t h e r sm all l i m i t s .
Our s t u d i e s h a v e shown t h a t , o f t h e s e a s s u m p tio n s , o n ly th e
l a s t a p p ears to be s t r i c t l y v a l i d .
tiv e fu n c tio n .
The c o n t a c t p r e s s u r e i s a v e r y s e n s i ­
The d i s c o n t i n u i t i e s i n t h e w av eg u id e a t t h e p o i n t w here
t h e d e t e c t o r an d g e n e r a t o r a r e may a c t u a l l y be q u i t e l a r g e w it h o u t
s e r i o u s c o n se q u e n c e .
The g e n e r a t i o n o f h a rm o n ic s m u st o c c u r w i t h i n t h e
c o n f in e s o f th e w a v e g u id e , b u t t h e d e t e c t i o n may t a k e p la c e w i t h t h e
c r y s t a l o u t s i d e o f th e w a v e g u id e .
T h e se and o th e r c r i t e r i a d e r iv e d fro m t h e s t u d i e s o u t l i n e d i n
t h i s w o rk p ro v id e d a c l e a r c u t s e t o f r u l e s b y w h ic h a new d e t e c t o r w as
d e s ig n e d .
I t w as a v e r y s im p le c h o ic e t o a tt e m p t t o b u i l d a new d e ­
t e c t o r b e f o r e w o ik in g o n a g e n e r a t o r .
w h ic h we h a v e n o t y e t s o lv e d .
The g e n e r a t o r o f f e r s a p ro b le m
I t w i l l b e rem em bered t h a t I t i s more
i m p o r ta n t to s e a l t h e g e n e r a t o r fro m t h e h a rm fu l e f f e c t s o f t he a tm o s­
p h e r e th a n i t w a s t o make a s e a le d d e t e c t o r .
The r e a s o n w h ich le d u s
t o a t t a c k t h e d e t e c t o r f i r s t w as t h a t n o m ethod f o r s e a l i n g t h e gen­
e r a t o r c o u ld b e d e v is e d w i t h o u t a p p r e c ia b ly a t t e n u a t i n g t h e e n e r g y f e d
i n t o t h e g e n e r a t o r fro m t h e k l y s t r o n .
T he d e s ig n c r i t e r i a f o r -the d e t e c t o r w e re s im p ly t h a t i t m ust
be e v a c u a b le , m e c h a n ic a lly c o n v e n ie n t t o u s e , v e r y p r e c i s e l y and a c c u ­
r a t e l y c o n s tr u c t e d , and i t s h o u ld i n c o r p o r a t e •the o b v io u s a d v a n ta g e s o f
th e r a d i a t i o n p ro b e s a l r e a d y d e v e lo p e d .
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40
I t i s a lw a y s r e l a t i v e l y e a s y t o b e c r i t i c a l o f a d e v i c e
d e v e lo p e d b y a n o t h e r g ro u p .
The p o i n t o f t h e d i s c u s s i o n t h a t f o ll o w s i s
n o t to b e c r i t i c a l b u t t o show t h a t th e p r i n c i p l e s d e m o n s tra te d b y t h i s
w ork com bined w i t h t h e d e s ig n i d e a s and s ta n d a r d s o f m e c h a n ic a l con­
s t r u c t i o n o f one o f th e men t o ■whom t h i s d i s s e r t a t i o n i s d e d ic a te d h a v e
r e s u l t e d i n a v e r y f i n e d e t e c t o r o f h ig h f r e q u e n c y m icrow aves.
The u n i t w as n o t made t o b e e v a c u a b le .
I n s t e a d , i t w as
d e s ig n e d so t h a t a s m a ll p o s i t i v e p r e s s u r e o f h e liu m can b e m a in ta in e d
i n s i d e t h e w av e g u id e an d t h e r e f o r e o n th e c r y s t a l .
The m eth o d s u se d t o c o n s t r u c t t h e d e t e c t o r w ere b a s e d on t h e
r e q u ire m e n t t h a t t h e h o l e s i n t h e w av eg u id e i n t o w h ich t h e c r y s t a l and
c a tw h is k e r a r e i n s t a l l e d m u st b e c o a x i a l t o w i t h i n l e s s th a n .0 0 1 * .
The
m ounting b lo c k s w h ic h c o n t a i n t h e c a tw h is k e r s tu d and c r y s t a l h o l d e r
m u st b e no l e s s c o a x i a l .
I t w as in te n d e d t h a t t h e c r y s t a l c o u ld b e
i n s t a l l e d i n th e d e t e c t o r w i t h o u t t h e s l i g h t e s t d a n g e r o f i t s b e i n g '
dam aged.
I n a d d i t i o n , t h e i n s t a l l a t i o n s h o u ld r e q u i r e no s p e c i a l a b i l i ­
t i e s a t o b s e r v a t i o n , l i t t l e tjm e and o n ly r e a s o n a b le c a r e .
The same
t h i n g s a p p ly to t h e h a n d lin g o f t h e c a tw h is k e r p r o b e .
As a r e s u l t o f t h e s e d e s ig n c o n s id e r a t i o n s , th e new d e t e c t o r
can b e assem b led and made o p e r a t i v e i n a few m in u te s .
T h is com pares w i t h
lo n g p e r i o d s o f t e d i o u s p r e l i m i n a i y p r e p a r a t i o n n e c e s s a r y t o s e t up an d
o p e r a te t h e e a r l i e r t y p e .
T he c r y s t a l and c a tw h is k e r i n v a r i a b l y make con­
t a c t w ith o u t s h o r t i n g and w i t h o u t a n eed f o r c h e c k in g f i n a l o r i e n t a t i o n .
The d i f f e r e n t i a l sc re w m ethod f o r r e g u l a t i n g c r y s t a l —c a tw h is k e r
c o n ta c t p re ss u re h as b een re p la c e d .
I t w as p o s s i b l e t o r e g u l a t e th e
c r y s t a l t r a v e l p e r t u r n o f a n a d j u s t i n g sc re w t o a b o u t .0 0 4 ” i n a d i f f e r
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41
e n t w ay.
An 0 -8 0 screw b e a r in g on a l e v e r h a v in g a t r a v e l r a t i o o f 4 to
1 g iv e s 240 t u r n s t o t h e in c h o r s l i g h t l y m ore th a n .0 0 4 " p e r t u r n .
Th®
l e v e r i s s p r in g - lo a d e d a g i n s t th e screw ; t h e c r y s t a l h o l d e r i s s p r i n g lo a d e d a g a i n s t th e l e v e r .
T h is method seems to g iv e v e r y s a t i s f a c t o r y
and s t a b l e c o n t r o l o f p r e s s u r e a d ju s tm e n t; and i t d o e s so i n a sim p le
w ay.
The r a d i a t i o n p ro c e b o tto m s on a s h o u ld e r sc 1faat t h e a n te n n a
i s alw ay s s i t u a t e d i n th e same p la c e i n t h e w a v e g u id e .
The p ro b e i s i n ­
s u la t e d by means o f a h o llo w c y lin d e r o f T eflo n w h ic h w as c a r e f u l l y
d r i l l e d to f i t i t .
The e x t e r n a l s u r f a c e of t h e T e flo n w as c u t to s i z e w
w h ile mounted on th e p ro b e so t h a t a l l e le m e n ts a r e c o n c e n t r i c .
C o n s tr u c tio n o f c a tw h is k e rs fo llo w e d t h e te c h n iq u e s o u t l i n e d
e a rlie r.
I t h a s b een found t h a t , a lth o u g h s o ld e r e d p r o b e s w ork much
b e t t e r , th e y a r e n o t immune to c o r r o s i o n .
The s o f t s o ld e r t u r n s i n t o a n
o x id e powder a f t e r t h e w ire h a s been sh a rp e n e d s e v e r a l tim e s .
A way i s
b ein g so u g h t t o e l i m i n a t e t h i s c o r r o s io n and th e l o s s o f .s e n s i t i v i t y
w hich alw a y s o c c u r s .
I t was p ro p o sed e a r l i e r t h a t t h e u s e o f .0 0 1 " tu n g s te n w ir e
would le a d t o im proved p c i n t l i f e and s e n s i t i v i t y t o h ig h e r h a rm o n ic s.
Some .0 0 1 ” w ire w a s o b ta in e d and t e s t e d in t h e new d e t e c t o r a s w e ll a s i n
th e o t h e r u n i t s .
T h is p a r t i c u l a r w ir e w as to o s o f t t o e x e r t s u f f i c i e n t
p r e s s u r e on th e c r y s t a l an d , a s a r e s u l t , gave o n ly m odest am ounts o f
e n e rg y .
A t p r e s e n t , i t seems b e s t to re d u c e .002" w ir e t o t h e d e s ir e d
t h i n n e s s by e l e c t r o p c i i s h i n g .
I n f a c t , i t i s n e c e s s a r y to e l e c t r o p o l i s h
m ost o f t h e l e n g t h . o f th e c a tw h is k e r e a c h tim e th e p c i n t i s r e s h a rp e n e d .
As a r e s u l t , th e w ir e i s g r a d u a lly made th i n n e r u n t i l t h e s o ld e r e d
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
j o i n t becomes to o c o rro d e d f o r s e n s i t i v e r e ^ o n s e .
The f a c t t h a t n o t
a l l th e l e n g th o f the w ir e i s th in n e d down a c c o u n ts f o r p a r t o f t h e
co m p a ra tiv e s tr e n g t h o f th e r e s u l t i n g c a tw h is k e r s .
,
I t ap p e a rs a ls o t h a t ,
once h e a te d t o r e d n e s s , th e tu n g s te n w ir e no lo n g e r i s u s e f u l a s a r a d i ­
a tio n sen so r.
D e t a i l s o f t h e c o n s tr u c tio n o f t h e new d e t e c t o r a r e g iv e n i n
d raw in g s o f e a c h o f th e p a r t s .
A p h o to g ra p h o f t h e a ssem b ly i s a l s o
in c lu d e d .
P e rfo rm a n c e :
R epeated t e s t s o f th e new d e t e c t o r
ott
t h a t i t f u n c tio n s
a t l e a s t a s w e ll a s th e m o d ifie d v e r s i o n s o f th o s e i t w as d e s ig n e d t o
re p la c e .
The o u tp u t o f e n e rg y assum es th e same p a t t e r n a s t h a t shown
b y th e a n te n n a -e q u ip p e d d e v ic e s .
smooth and r e p r o d u c ib le tu n in g .
«
u n i t w as asse m b le d .
The n e w ly -d e sig n e d end p lu n g e r p e r m its
E n e rg y w as o b ta in e d t h e f i r s t tim e t h e
I t h a s b een o b ta in e d w it h o u t f a i l e a c h tim e a t e s t
w as p e rfo rm e d .
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43
DISCUSSION
The o b j e c t i v e s o f t h i s r e s e a r c h w e re t o s tu d y and p o s s i b l y to
d e f in e some o f th e p a r a m e te rs g o v e rn in g t h e g e n e r a tio n and d e t e c t i o n o f
m i l l i m e t e r w av es so t h a t i t w ould b e p o s s i b l e t o d e s ig n an im proved
sy stem f o r t h i s p u rp o s e .
The e x i s t i n g s y ste m g a v e h arm o n ic e n e rg y
w h ich w as h ig h a t c e r t a i n f r e q u e n c i e s and z e r o o r i n t e r m e d i a t e a t o t h e r
f r e q u e n c i e s i n t h e o p e r a tin g r a n g e .
The K -band v id e o s p e c tr o m e te r s
w ere s e e n t o h a v e th e same p e r i o d i c p a t t e r n o f r e s p o n s e .
. A u n if y in g p r i n c i p l e w as s o u g h t i n a m odel o f t h e r a d i a t i o n .
T he
model w as t h a t o f a s ta n d in g w ave o f r a d i a t i o n w hose nta-r-fmwe f a l l i n g on
th e r a d i a t i o n p ro b e moves away from t h e p r o b e a s t h e f r e q u e n c y i s
ch an g ed .
The p e r i o d i c r e s p o n s e p a t t e r n s w e re se e n t o be a l o g i c a l
re s u lt.
I t w a s, o f c o u r s e , d e s i r a b l e t o p r o v id e a co n tin u u m o f e n e r g y .
T h is w as done w i t h t h e a n te n n a e whose d e s ig n w as b ased on a c o n s id e r a t i o n
o f th e s ta n d in g w ave m o d el.
The u s e f u l n e s s o f t h e m odel i n e x p l a i n i n g th e r e s p o n s e p a t t e r n s and
i n f o r m u la tin g th e a n te n n a d e s ig n a r g u e s v e r y s t r o n g l y f o r i t s s e r i o u s
c o n s id e r a t i o n i n d e s ig n o f m icrow ave s p e c tr o m e te r s o p e r a t i n g a t o t h e r
fre q u e n c ie s .
S im p ly to b u i l d a sy stem t o d e t e c t r a d i a t i o n m ore o r le 3 S con­
t i n u o u s l y w as n o t s u f f i c i e n t .
I t w as n e c e s s a r y t o o b ta in enough e n e rg y
w ith w h ich t o o b s e rv e r o t a t i o n a l s p e c t r a .
I t m u st b e n o te d t h a t th e new
sy stem a l s o g iv e s e n e rg y i n a p e r i o d i c p a t t e r n b u t h a s t h e v i r t u e t h a t
t h e am ount o f h arm o n ic e n e rg y n e v e r d r o p s to z e r o e x c e p t w h ere k l y s t o n
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
44-
o u t p u t h a p p en s t o b e lo w .
T h ese o b s e r v a t io n s w e re made w ith o u t h a v in g
th e g a s c e l l b etw een th e g e n e r a t o r and t h e d e t e c t o r .
S in c e t h e g a s c e l l
a t t e n u a t e s th e r a d i a t i o n a p p r e c i a b l y , t h e o u tp u t g o e s t o z e r o o c c a s io n ­
a lly .
When t h i s h a p p e n s e n e r g y c a n b e o b ta in e d by r a t h e r s im p le ad ­
j u s t m e n t s o f t h e end p l u n g e r s .
I t w as t o be e x p e c te d t h a t t h e a m p litu d e o f maximum o u t p u t o f h a r ­
m onics p ro d u c e d b y l i n e a r p r o b e s w ould b e g r e a t e r th a n t h a t g iv e n by th e
a n te n n a .
T h is w a s t h e o n ly d is a d v a n ta g e o f t h e a n te n n a e w h ic h te n d to
a v e ra g e o v e r an a n t i - n o d e g i v i n g a lo w e r b u t w id e r r e s p o n s e .
The l e s s e r
a m p litu d e p ro d u c ed by th e- a n te n n a w as overcom e b y new and s p e c i a l l y
t r e a t e d c r y s t a l s a s w e l l a s im proved f a b r i c a t i o n o f tu n g s te n c a tw h is k e r s
on b r a s s p r o b e s .
P r e s e n t l y , i t a p p e a r s t h a t t h e r e s p o n s e o b s e rv e d i s
e q u i v a l e n t i n a m p litu d e b u t f a r more b ro ad i n f re q u e n c y c o v e ra g e thaw
th e r e s p o n s e o f l i n e a r p r o b e s .
A l o g i c a l outcom e o f t h i s w ork w as t h e d e v e lo p m e n t o f a s u b s t a n t i a l ­
l y im proved d e s ig n f o r t h e d e t e c t o r and g e n e r a t o r .
Much of t h e e x p e r i­
m e n ta l d i f f i c u l t y w as d i r e c t l y r e l a t e d t o a l a c k o f a c c u r a te c o n s t r u c t i o n .
T h is w as p a r t l y overcom e i n t h e m o d ifie d u n i t s b u t th e s e tu p tim e w as
s t i l l lo n g , d u e t o t h e f a c t t h a t t h e l a c k o f a c c u r a c y h ad t o b e overcom e
b y a s u b s t a n t i a l e f f o r t aim ed a t p e r f e c t a lig n m e n t o f th e c a tw h is k e r .
Im p ro v in g c o n s t r u c t i o n a c c u r a c y b y a f a c t o r o f t e n l e d t o g r e a t e r
t o l e r a n c e i n s e t t i n g up p r o b e s .
The s i m p l i f i e d p ro b e s and c r y s t a l
h o l d e r s may be i n s t a l l e d i n m in u te s and c h a n g e d e a s i l y .
T h e re a r e many
o t h e r m e c h a n ic a l f e a t u r e s w h ic h e l i m i n a t e tim e consum ing s t e p s , d a n g e r
o f dam aging p ro b e and c r y s t a l , and t h e ch an g e o f f a i l u r e t o g e t e n e rg y .
P e rfo rm a n ce o f t h e new d e t e c t o r i s a t l e a s t a s good a s t h a t o f a
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
U5
m o d ifie d d e t e c t o r .
The p r o v is io n f o r o p e r a tio n a s a s e a le d u n i t i n s u r e s
lo n g te rm s e n s i t i v i t y .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
SUMMARY
The c r i t e r i o n f o r s u c c e s s i n t h i s w ork w as t h a t o f p r o v id in g , bymeans o f h arm o n ic g e n e r a t o r s and d e t e c t o r s , s u f f i c i e n t e n e r g y to o p e r a te
a v id e o s p e c tro m e te r o v e r a w ide ra n g e i n a c o n v e n ie n t m anner.
Thi s w as
a q u a l i t a t i v e s ta n d a r d , b u t i t w as one "which n e e d s no d e f e n s e .
The
f o llo w in g t h r e e p a r a g ra p h s a r e in te n d e d to show t h a t t h i s c r i t e r i o n h a s
been m e t.
1.
F requency Range o f O p e r a tio n .
I t w as f i r s t p o in te d o u t t h a t s u f f i c i e n t am ounts o f h arm o n ic
e n e rg y w ere a v a i l a b l e o n ly i n tw o o r t h r e e n a rro w f re q u e n c y r a n g e s .
The
new com ponents d e v e lo p e d d u rin g t h i s w ork have been o p e r a te d fro m 20 to
26 KMC. p ro d u c in g e n e r g y a t 4-th and h ig h e r h a rm o n ic s .
I t w as p o s s i b l e
t o c a r r y o u t t h i s o p e r a tio n o v e r a p p r e c i a b le f r a c t i o n s o f th e ra n g e
w ith o u t change o f tu n in g p a r a m e te r s .
2.
C o n v en ien ce.
The s e tu p tim e w as f o rm e r ly v e r y lo n g and e s p e c i a l l y burdensom e
i n t h a t i t w as n o t c o n f i d e n t ly known t h a t e n e r g y would b e o b ta in e d .
new com ponents h av e been shown t o be e a s y to u s e .
up and g iv e e n e rg y i n v a r i a b l y .
The
They a r e s w i f t l y s e t
The am ount o f e n e rg y i s u s u a l l y s u f f i c i e n t
t o p e r m it o b s e r v a tio n o f s p e c t r a i f th e c r y s t a l s are f r e s h l y p o lis h e d ,
th e c a tw h is k e r i s n o t c o rro d e d and th e k l y s t r o n o u tp u t i s n o rm a l.
3.
O p e ra tin g L i f e .
The o p e r a t i n g l i f e o f t h e harm onic g e n e r a to r and d e t e c t o r w as
shown t o be a f u n c t i o n o f t h e i r e x p o s u re t o h u m id ity .
I t w as a l s o shown
t h a t th e harm onic g e n e r a t o r c r y s t a l d e t e r i o r a t e d i r r e v e r s i b l y i n u s e .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
U1
To e li m i n a t e t h i s d e t e r i o r a t i o n , s e a le d u n i t s w ere d e v e lo p e d .
th e s e h a v e n o t b een th o ro u g h ly t e s t e d f o r lo n g l i f e ,
A lth o u g h
t e s t s on o t h e r u n i t s
p r e s e r v e d i n vacuum d e m o n stra te d t h a t t h e i r u s e f u l l i f e w as in c r e a s e d
many f o l d .
M ach in in g M eth o d s: ' P e rh a p s t h e m o st im p o r ta n t m ethod in v o lv e d i n t h i s
w ork w as th e a d a p t a t i o n o f w a tc h m aking te c h n o lo g y to t h e d e s ig n and manu­
f a c t u r e o f com ponents.
The p r e c i s i o n and a c c u r a c y r e q u ir e d h e r e w as
c e r t a i n l y an o r d e r o f m ag n itu d e b e t t e r th a n t h a t p r o v id e d by n o rm al
m a ch in in g m eth o d s.
The t o t a l e r r o r i n t h e new d e t e c t o r c a tw h is k e r an d
c r y s t a l p o s i t i o n i n g i s a p p r o x im a te ly .0003 i n c h e s .
T h is p r e c i s i o n m akes
s e tu p p r o c e d u re s much l e s s r i g o r o u s .
The u se o f t h i s te c h n o lo g y a l s o p e r m itte d d e s ig n and con­
s t r u c t i o n o f a w ide v a r i e t y o f r a d i a t i o n p ro b e s and f a b r i c a t i o n o f
c r y s t a l s i n t o fo rm s u s e f u l a s s e m ic o n d u c to rs .
The d e s ig n o f th e new
d e t e c t o r was b a se d on o b s e r v a t io n s made w ith t h e s e (and o th e r ) com­
p o n e n ts .
One o f th e r e s u l t s o f a p p l i c a t i o n o f t h e s e te c h n iq u e s w as a
s u b s t a n t i a l r e d u c tio n i n s i z e o f th e w h o le u n i t .
The Model o f t h e R a d i a t i o n ;
The a n te n n a d e s ig n r e s u l t e d fro m c o n s id e r ­
a t i o n o f a sim p le m odel o f t h e r a d i a t i o n .
The m odel w as t h a t o f a
s ta n d in g wave whose n - t h maximum moved a s a f u n c t i o n o f th e fre q u e n c y .
The a n te n n a w as in te n d e d t o p r o v id e a r a d i a t i o n s e n s o r c a p a b le o f s e e in g
a t l e a s t p a r t s o f maxima o f a ra n g e o f f r e q u e n c i e s .
T h a t i t d id so
te n d s t o c o n firm th e c o r r e c t n e s s o f t h e model,,
In d e p e n d e n t T e s t f o r H arm onic O u tp u t;
A v a lu a b le t e s t w as d e v e lo p e d f o r
d e te r m in in g w h e th e r th e g e n e r a t o r w as f u n c t i o n i n g w ith o u t h a v in g a
w o rk in g d e t e c t o r .
T h is in d e p e n d e n t t e s t i s a m easure o f t h e n o n - l i n e a r i t y
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
o f g e n e r a to r d io d e r e s p o n s e t o fu n d a m e n ta l r a d i a t i o n from t h e k l y s t r o n .
I t s e r v e s t o d e te r m in e w h e th e r o r n o t th e g e n e r a t o r i s f u n c t io n i n g and
a p p r o x im a te ly how w e l l .
C o n s e q u e n tly , i t p r o v id e s a q u a l i t a t i v e t e s t
f o r how w e l l t h e d e t e c t o r s h o u ld be w o rk in g .
W ith o u t such a t e s t , one
h a s no know ledge o f "the sy ste m u n l e s s i t i s w o rk in g w e l l .
S p e c i a l T re a tm e n t o f C a tw h is k e r W ire ?
A m ethod w a s d e v e lo p e d f o r r e ­
m oving th e b la c k c o a tin g on tu n g s te n w i r e .
I t s i n t e r f e r e n c e w ith de­
t e c t i o n o f r a d i a t i o n v a r i.e s w ith th e t h i c k n e s s o f t h e c o a tin g .
I t p re­
v e n t s f o rm a tio n o f a good n i c k e l p l a t e f i l m n e c e s s a r y f o r s o l d e r i n g
p ro b es.
Removal o f t h e c o a tin g i s done by a h ig h s p e e d , s h o r t d u r a t io n
e l e c t r o p o l i s h i n g w h ic h m ust b e r e p e a te d e a c h tim e t h e p ro b e i s s h a rp e n e d .
C r y s ta l P o lis h in g :
A c r y s t a l w h ich h a s l o s t i t s s e n s i t i v i t y may be
renewed b y r e p o l i s h i n g .
Two s t e p s a r e r e q u i r e d .
The f i r s t in v o lv e s
rem o v al o f th e o ld s u r f a c e b y m eans o f a h a r d A rk an sas s to n e .
The
second r e g e n e r a t e s t h e h ig h p o l i s h v i a b u f f i n g on a f l a t , tim e l a p
ch a rg ed w ith s t a i n l e s s s t e e l r o u g e .
New R o t a t i o n a l L in e o f NO?:
A r o t a t i o n a l l i n e o f t h e a sy m m etric t o p ,
N02j w as o b se rv e d a t 1 2 3 ,2 2 1 .8 8 MC.
P r e d ic te d R o t a t i o n a l S p ectru m o f OF^:
The f r e q u e n c i e s o f a nunfoer o f
l i n e s o f th e c a l c u l a t e d r o t a t i o n a l sp e c tru m o f oxygen d i f l u o r i d e a r e
ta b u l a t e d i n t h e A p p endix.
D e t a i l e d D raw ings o f th e P a r t s o f th e New D e t e c t o r ;
c o n ta in s a s e r i e s o f d ra w in g s fro m w hich i t
The A ppendix a l s o
sh o u ld be p o s s i b l e to con­
s t r u c t a d u p l i c a t e o f t h e new d e t e c t o r .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
49
APPENDIX
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Energy Level Needed
figure
i
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
-TYPICAL RESPONSE PATTERN FOR LINEAR PROBES
10
.Response After
^
20
21
22
Two Hours
25
Fundamental Frequency in Kilomegacycles
24
FIGURE 2
r= iic
=R
It'
1c i 5L
T
u
Oross Sections of
a, Modified detector showing antenna probe.
b, Linear probe in unmodified detector.
c, Modified generator with antenna in K-band,
d, Linear probe in. unnodified generator.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 1'
a. RADIATION PROBE
3.7«» 3
0
‘j.YC
j. 10
J-O
— w T
)X-1'O
" .V
iMo tl £ -
NOTES:
3
1.
Material: soft brass, round stock.
2.
Finish: high polish except as noted.
3.
Angle and finish not critical on stub end.
4.
Tolerance: .005
noted hereafter.
5.
Dimensions in millimeters, i.e., 1 mm = .040".
6.
Catwhisker: .002”, i.e., .05 nun Tungsten.
Shape: .4- mm radius, .1 mm linear dist. from
probe. 2.0 mm from loop to end.
7.
Specify: Tungsten/brass connection, on electro
polished and nickle plated wire, solder (m.p.
about 100°F) not to exceed .1 mm on exposed
wire.
or .000125" except as
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 2
PROBE INSULATOR
r-
NOTES:
1.
Material: Round Teflon or Kel-F.
2.
Hole drilled to fit probe before outside
surface is cut.
3.
Probe plus insulator chucked to cut 3.20 diam.
4.
Finish: high polish.
5.
Tolerance: .005 mm all dimensions.
PROBE TUBE
i Natt- 3
NOTES:
1.
Brass, soft, round.
2.
Hole highly polished and concentric to .005 mm
with all cylindrical surfaces.
3.
Make seal cap from watch crown by drilling out
3 mm hole in top. Make 2. Cut threads to fit.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 5
ADAPTER, PROBE TUBE TO CABLE CONNECTER
L-f.&
Note. S, 2
NOTES: 1.
Material: round brass stock.
2.
F in is h .: sm o o th e o . d . , p o l i s h 4-. 9 9 i sn u g f i t on P rob e t u b e . ~
3.
Threads i. d. to fit Amphenol-31-101-UG-206/U.
cL. t o
Assembly: snug fit on probe tube and solder.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 4-
WAVEGUIDE
Cross Section
1.0
I
.1
■!!';
—►
it-
ft
♦
j.io
--2
“ !f=5a..^o
f
A *=r
r3
.'n
•3f
1■
7
------- 71
N ctz. 3
/7
lit"1!!
H
/V U «-I
NOTES:
1. Material: Coin silver G—hand waveguide.Waveguide: 1 x 2 int, std. ext.
2. Finish std except fine wherever drilled or
turned.
3.
Turned to fit end seal cap.
4-. Turned to fit Duke flange.
5.
locate hole center from center of internal
widest surface. Tolerance .01 mm.
6.
All holes concentric to .005 nim.
7.
5.99 id to fit same od prohe tube and crystal
tube.
8.
Waveguide cut at center so that remainder is
.30 mm thick. Cut - bevel to fit insulator.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 5
END SEAL CAP: (Note 3* Dwg. — 4)
v
NOTES:
1.
Soft "brass, round stock.
2.
Finish fine 3.80 to 2.20.
3.
Assembly: push, fit on waveguide and solder,
0—ring groove out.
CRYSTAL TUBE
1r
f jvote. V
NOTES:
1.
Soft brass, round stock
2.
Hole is bored concentric to .003 mm with
4.00 i. d.
3.
Finish: Std except polish i. d. and 4.00'i.
Latter to fit waveguide hole.
4.
Cut and thread to fit crown seal cap.
Dwg—2, Note 3. Rubber washer 3.80 o. d.
2.20 i. d., .50 thick (2 ea.).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 6
CRYSTAL PROBE
■
-
J \.o
ID H
<
(i.C
NOTES:
1.
*
Material: soft "brass, round stock.
2.
Finish: high polish o. d.
3.
Crystal pin .25 mm diam. installed exactly
concentric
END PLUNGER PARTS
ROTOR
jf
ht
\ * Nc t
NOTES:
e.
1.
Soft brass, round stock.
2.
Finish stock except polish 5.4-5 diam. face
and opposite end.
5.
Furnish cap screw 2 mm root, tap to fit.
Thread 7 mm length for 1.50 root dia. (std. 0-80).
4-.
Assembly: cap screw and rubber washer.
spring 6 mm long, 3.90 i. d.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Also,
BRAtfIRG 7
KBUEUED KNOB
3
A
~ ^v
^
--------------------
S'.
= 3
ROTES:
1.
Soft brass, round stock.
2.
Bearing surface 8.5 o. d.
Stock finish, except knurled.
3*
Drill and tap for Allen set screw.
STATOR
.Vo*«-3
2
h
t
I T~
■1 1
1' - L. - _
_, :
r
a. J
s.
ris»
"
”
i
w
j _____
/v.
ROTES: 1.
r- - j
.
—
Z_L_
i
Soft brass, round stock.
2.
Finish all smoothe.
3*
Drill and tap for cap screw set,
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWIEG 8
PLUNGER
3. 7 « / i v
N at <■ c/
N a U l f7
•
NOTES:
!*
trr
1.
Sheet; brass and round stock.
2.
Solder assembly.
3.
Hand fit to G-band approx. 1.2 x 2.2,
4.
Cut std 0—80 thread.
CRYSTAL POSITIONER PARTS
One end plunger assembly less plunger.
See Dwg1s 6 and 7.
FINE ADJUST SCREW
r
J
- 7.
±
aL ^t.4 Ah.&^s=_
-*®
\
g r , / / v ft
3 c ircj
S m ^
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 9
LEVERS
iJ.O
o
No 1
ROTES:
Sheet; brass 1 mm thick.
2.
Smoothe finish all.
Break edges.
Li
3 .0
iili
II
J.c
S '
i u
Y.J
i a .
§or-
-
S
~*}
cP Q
4
~T
j* »"
_1_
it.
ROTES: 1.
*H ot t i
lb
c
m— 3.t
J,
S .3 -
y 4-
./v/.fe- *
J
Sheet brass 1 mm thick
2.
Smoothe finish all.
Break edges.
3.
Drill 1.60 to fit Fine adj. screw.
4. Drill
1.60 to fit;rivet] through Ro. 1 above,
5. Drill
1.60 to fit rivet/axis through frame.
6. Drill and tap for 3.2 thr./mm.
rt. L to align w/Ho. 2 above.
be on top of II.
Fold up at
Lever I to
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DEALING- 10
Not <- S~
-6
u.7
NOTES:
1.
Brass sheet, 1 mm.
2.
Smoothe finish, break edges.
3*
Hole to spring from lever II.
4-.
Fold down rt. /_
5.
locate from fold., drill1.60, iiote
6.
locate from 5.
7*
Fold around stator, Dwg-7,drill
fasten stator.
8.
Assembly requires hand fit.
5 Dwg -9
at assembly
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
DRAWING 11
FRAME TO WAVEGUIDE CONNECTOR
h ' 1 -!
h 71
(•«-i
NOTES:
1.
Brass.
2.
Break edges.
3.
Set screw 1/8", e.g., face off end.
4.
Assembly: fit with, care to frame (Note
Dwg-10) and solder. See Photo.
' SCREW
s:
1
a.
_ i___
NOTES:
1.
Brass
2.
Assemble to levers I and II
3.
See Note 4 Dwg-8
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
CALCULATION' OF ENERGY LEVELS AND ROTATIONAL LINES OF 0F2
The m ethods f o r c a l c u l a t i n g r o t a t i o n a l l i n e s o f a s ymme t r i c to p
m o le c u le s a r e g iv e n b y T o w n e s ^ i n w hose t e x t may b e fo u n d t h e many
o rig in a l re fe re n c e s.
'
The l i n e f r e q u e n c i e s w ere c a l c u l a t e d two w a y s .
One in v o lv e d t h e u s e
o f a s ymme t r y p a r a m e te r t a b l e s i n Townes w i t h t h e a i d o f w h ic h I t i s r e l a ­
t i v e l y e a s y t o do t h e c a l c u l a t i o n s on a d e s k c a l c u l a t o r .
TSxe second
in v o lv e d u s e o f a n IBM 650 c a l c u l a t o r on w h ic h t h e s o l u t i o n s t o t h e se c u ­
l a r e q u a tio n s w ere program m ed.
fo u n d i n th e book b y G ordy
C2)
.
R e f e r e n c e s t o t h e s e e q u a tio n s may b e
i t w as o f I n t e r e s t t o n o te t h a t v a l u e s
c a l c u l a t e d b o th w ays a g re e d t o w i t h i n a fe w p a r t s i n t e n th o u s a n d .
program m ing o f th e IBf.f 650 w as done b y M r. Jam es B e a l.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
The
ENERGY LEVELS IDE J - 5 o r LESS
J (K p , Kc ) *
0 (0 , 0 )
1 ( 0 ,1 )
1 ( 1 ,1 )
1 ( 1 ,0 )
E (K p , Kq)
0
2 0 ,8 8 7 .7 i n m e g a c y c le s
7 1 ,0 7 2 .7
7 2 ,8 3 3 .4
2 ( 0 ,2 )
2 ( 1 ,2 )
2 ( 1 ,1 )
2 ( 2 ,2 )
2 ( 2 ,0 )
6 2 ,7 8 6 .7
1 1 1 ,1 4 4 .8
1 1 6 ,5 9 9 .1
2 6 6 ,9 8 1 .9
2 6 7 ,0 3 0 .5
3 ( 0 ,3 )
3 ( 1 ,3 )
3 ( 1 ,2 )
3 ( 2 ,2 )
3 ( 2 ,1 )
3 ( 3 ,1 )
3 ( 3 ,0 )
1 2 5 ,4 2 8 .0
1 7 1 ,2 3 3 .3
1 8 2 ,1 3 0 .8
3 2 9 ,8 1 7 .2
3 3 0 ,0 5 9 .8
5 8 5 ,0 3 0 .4
5 8 5 ,0 3 1 .2
4 ( 0 ,4 )
4 ( 1 ,4 )
4 ( 1 ,3 )
4 ( 2 ,3 )
4 ( 2 ,2 )
4 ( 3 ,2 )
4 ( 3 ,1 )
4 ( 4 ,1 )
4 ( 4 ,0 )
2 0 8 ,7 2 4 .9
2 5 1 ,2 7 2 .5 ;
2 6 9 ,4 7 7 .8
4 1 3 ,5 5 9 .8
4 1 4 ,2 8 6 .0
6 6 8 ,9 0 5 .6
6 6 3 ,9 1 1 .2
1 ,0 2 6 ,0 7 5 .2
1 ,0 2 6 ,0 7 5 .2
5 ( 0 ,5 )
5 ( 1 ,5 )
5 ( 1 ,4 )
5 ( 2 ,4 )
5 ( 2 ,3 )
5 ( 3 ,3 )
5 ( 3 ,2 )
5 (4 , 2 )
5 ( 4 ,1 )
5 ( 5 ,1 )
5 ( 5 ,0 )
3 1 2 ,4 8 9 .4
3 5 1 ,2 4 8 .6
3 7 8 ,4 9 7 .4
5 1 8 ,1 7 7 .4
5 1 9 ,8 6 4 .4
7 7 3 ,7 8 9 .6
7 7 3 ,8 1 2 .3
1 , 130 , 9 0 8 .6
1 ,1 3 0 ,9 0 8 .7
1 ,5 9 0 .1 3 8 .3
1 ,5 9 0 ,1 3 8 .3
* N o ta tio n s
Kp i s K f o r p r o l a t e l i m i t , KQ i s K f o r o b l a t e l i m i t .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
PERMITTED TRANSITIONS
The s e l e c t i o n r u l e s a r e t h a t a J = 0 , I 1 ; 4
- 3-
1$ and AKQ ** - 1 ,
Symmetry dem ands t h a t t r a n s i t i o n s o c c u r o n ly betw een s t a t e s f o r
w h ich Kp, Kq have t h e f o llo w in g e v e n n e s s an d o d d n e ssr
o e —» e o .
e e —*
00
or
A c o n v e n ie n t m ethod f o r d e te r m in in g t r a n s i t i o n s i s to p l o t a~n
p o s s i b l e v a lu e s J th e i n d i c e s a s b o th o r d in a t e and a b s c i s s a and t o ma-rfr
i n p o i n t s c o rre s p o n d in g to t r a n s i t i o n s .
w h ere A J = 0 , oe-— > e o .
F o r .exam ple, 1 ( 1 ,0 ) — > 1 ( 0 ,1 )
I f a l l p o s s ib le p o in ts a re p lo tte d , th e re
a p p e a r s a s y m m e tric a l p a t t e r n w h ic h a i d s i n c h e c k in g r e s u l t s .
The f o llo w in g i s a l i s t o f t r a n s i t i o n s i n o r d e r o f f r e q u e n c y .
Range i n MC
Frequency
0 -1 0
10-20
2 0 -3 0
3 0 -4 0
4 0 -5 0
50-60
,
6 0 -7 0
7 0 -8 0
8 0 -9 0
9 0 -1 0 0
100-140
140-150
T r a n s itio n
D e sig n a tio n
8 ,2 8 6
1 4 ,2 8 3 .2
1 ( 1 , 1 ) —2 ( 0 ,2 )
2 ( 1 ,2 ) - 3 ( 0 ,3 ) “
P ( l,- 1 )
R ( -i,i)
3 5 ,0 6 2 .4
3 7 ,5 0 1 .6
4 ( 2 ,3 ) - 5 ( 1 ,4 )
3 ( 1 ,3 ) - 4 ( 0 ,4 )
R ( -l,l)
R ( -l,l)
5 1 ,9 4 5 .7
5 3 ,8 1 2 .4
5 6 ,7 0 2 .8
6 0 ,3 6 9 .4
6 0 ,7 2 2 .9
6 1 ,2 1 6 .9
6 3 ,0 3 7 .4
6 6 ,0 0 8 .0
7 1 ,0 7 2 .7
7 8 ,7 3 7 .3
8 4 ,8 5 1 .1
9 0 ,2 5 7 .1
9 5 ,8 0 7 .2
1 0 8 ,4 3 6 .6
1 2 5 ,8 4 4 .5
1 4 1 ,3 0 0 .0
1 4 2 ,5 2 3 .7
1 4 4 ,8 3 8 .0
1 4 7 ,9 2 9 .0
1 4 9 ,0 4 1 .2
1 ( 0 ,1 ) - 1 ( 1 ,0 )
2 ( 0 , 2 ) —2 ( 1 ,1 )
3 ( 0 ,3 ) - 3 ( l,2 )
3 ( 2 ,2 ) - 4 ( 1 ,3 )
4 (0 , 4 ) - 4 ( 1 , 3 )
4 ( 1 ,4 ) - 5 ( 0 ,5 )
4 ( 2 ,2 ) —5 ( 1 ,5 )
5 ( 0 ,5 ) - 5 (1 ,4 )
0( 0, 0 ) —1( 1, 1)
3 ( 2 , 1 ) —4 ( 1 ,4 )
2 ( 2 , 1 ) —3 ( 1 ,2 )
1 ( 0 ,1 ) - 2 ( 1 ,2 )
2 ( 2 , 0 ) —3 ( 1 ,3 )
2 ( 0 ,2 ) - 3 ( l,3 )
3 ( 0 ,3 ) - 4 ( l,4 )
5 ( 1 ,4 ) - 5 (2 ,3 )
4 ( 0 ,4 ) - 5 ( l,5 )
4 ( l,3 ) - 4 ( 2 ,2 )
3 ( 1 ,2 ) - 3 ( 2 ,1 )
4 ( 3 ,2 ) - 5 ( 2 ,3 )
Q (l,-D
Q ( l,- 1 )
Q ( l,- 1 )
P ( l,- 1 )
Q ( l,- 1 )
R ( -l,l)
P ( l ,- 3 )
Q ( l,- 1 )
R ( l,l)
P ( l,- 3 )
P ( l,- 1 )
R ( l,l)
R ( - l,3 )
R ( i,i)
R ( l,l)
Q (l,-l)
R (1 ,D
Q ( l,- 1 )
Q ( l,- 1 )
P ( - l,l)
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
1 5 0 -1 6 0
1 60-170
170-190
190-200
150,431.4150,'733. 8
1 5 5 ,8 3 7 .1
1 5 8 ,5 9 3 .9
1 6 2 ,2 8 7 .3
1 6 7 ,0 0 0 .0
1 7 0 ,4 7 1 .4
1 7 1 ,4 7 1 .4
1 9 4 ,1 4 8 .5
1 9 5 ,9 5 7 .8
2 ( l,l) - 2 ( 2 ,0 )
4 ( 3 ,1 ) - 5 ( 2 ,4 )
2 ( 1 ,2 ) —2 ( 2 ,1 )
3 ( l,3 ) - 3 ( 2 ,2 )
4 ( 1 ,4 ) - 4 ( 2 ,3 )
5 ( 1 ,5 ) —5 ( 2 ,4 )
3 ( 3 ,l) - 4 ( 2 ,2 )
3 ( 3 , 0 ) - 4 ( 2 ,3 )
l( l,0 ) - 2 ( 2 ,l)
1 ( 1 ,1 ) —2 ( 2 ,0 )
Q ( l,- 1 )
P ( l,- 3 )
Q ( l,- 1 )
Q ( l,- 1 )
Q ( l,- 1 )
Q (l,-D
P ( l,- l)
P ( l,- 3 )
R ( l,l)
R ( l,- 1 )
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
BIBLIOGRAPHY
1.
Townes, G .E. and A .L . Schawlow, "M icrow ave S p e c tr o s c o p y " ,
M cG raw -H ill Book Company, I n c . , New York (1 9 5 5 ).
2.
G o rd y , W ., W.V. S m ith , and R .F . T ram b aru lo , "M icrowave S p e c tro s c o p y " ,
Jo h n W iley and S o n s, i n c . , New York (1953) .
3.
S m ith , A .G ., W. G ordy, J .W. Simmons, and W.V. S m ith , P i y s . R e v .,
7 5 , 260 (1 9 4 9 ).
4.
J o h n s o n , C .M ., R .. T ram b aru lo , and W. G ordy, P h y s . R e v .,
8 4 , 1178 ( 1 9 5 1 ).
5.
K ing, W .C ., and W. G ordy, P h y s . R e v ., 9 3 , 407 (1 9 5 4 ).
6.
Cowan, M ., and W. G ordy, P h y s . R e v ., 1 0 4 , 5 5 1 -2 ( 1 9 5 6 ).
7.
T o lb e r g , W .E ., W. D. H en d erso n , and A l b e r t W. J a c h e , Rev. S c i . I n s t . ,
in p re s s .
8.
T o rre y , H.C. an d C.A. W hitm er, " C r y s t a l R e c t i f i e r s " , MIT R a d ia tio n
L a b o ra to r y S e r i e s , V o l. 1 7 , M cG raw -H ill Book Company, I n c . , New Y ork
(1 9 4 8 ).
9.
M ontgom ery, C .G ., "T e c h n iq u e s o f M icrowave M easu rem en ts", MIT
R a d ia tio n L a b o ra to ry S e r i e s , V o l. 1 1 , M cG raw -H ill Book Company, I n c . ,
New Y ork (1 9 4 7 ).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
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