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5H3}? Q, ‘E945.
P.‘ 'L. HARTMAN
2,403,444.
ELECTRON DIS CHARGE DEVICE
Filed May 51, 1941
2 Sheets—Sheet 1
-
M/l/ENTOR
‘By RLHARTMAN
Wm QM
' A T TOR/15V
July 9. 1946-
P. L. HARTMAN‘
2,403,444
ELECTRON DI SCHARGE DEVICE
‘Filed May 51, 1941
2 Sheets-Sheet 2
INVENTOR
By P, L. HARTMAA/
A TTQRNEK
Patented July 9, 1,946
2,403,444
, UNITED STATES PATENT OFFICE
2,403,444
I
ELECTRON DISCHARGE DEVICE
‘
Paul L. Hartman, New York, N. Y., assignor to
Bell Telephone Laboratories, Incorporated,
New York, N. Y., a corporation of New York
Application May 31, 1941, Serial No. 395,948
11 Claims.
1
(Cl. 250-275)
2
This invention relates to electron discharge de
are appreciable and hence reduce the operating
vices and more particularly to such devices espe
efliciency of the device.
cially suitable for use as ampli?ers at ultra-high
One object of this invention is to extend the
frequencies, such as frequencies in the centimeter
frequency range of operation of ultra-short wave
wave-length range.
electron discharge devices.
>
In ultra-high frequency electron discharge ap
Another object of this invention is to facili
paratus including an electronic device, the elec
tate the attainment of’ a very high impedance
trodes of the device and the leading-in conduc
across the input elements of electron discharge
tors therefor constitute a large part of the cir
devices operable at extremely high frequencies.
cuit and the interelectrode impedances play a 10
Still another object of this invention is to effec
major part in determining the upper frequency
tively segregate the input‘ and output elements
limit ;of the range in which the apparatus may
of electron discharge devices whereby interac
be operated. Also in such apparatus, a very
tion therebetween is minimized.
high impedance across the input elements of the
‘ A further object of this invention is to reduce
electronic device usually is desired and to this 15 dielectric losses in ultra-high frequency elec
end a distributed constant external circuit, such
tronic discharge devices and thereby to increase
as a coaxial line, short-circuited at the end there
the operating ef?ciency of such devices.
ofremote from- the electronic device, is associ
In one illustrative embodiment of this inven
ated with the electrodes, such as the cathode and
tion, a grounded grid centimeter wave-length
control electrode or grid, of the device.
20 ampli?er comprises elongated parallel cathode,
The end impedance of a short-circuited coax
control grid and anode electrodes having uni
ial line of a length somewhat less than a quarter
formly spaced juxtaposed surfaces and mounted
wave-length is primarily inductive. The imped
within an enclosing vessel having a metallic wall
ance of an open line, such as simulated by'a
or base portion electrically integral with the con
pair of electrodes is primarily capacitive. If the 25 trol grid and to which the leading-in conductors
short-circuited and open-ended lines are con
for the cathode and anode are hermetically
nected together, a very high impedance is ob
sealed, the Wall or base portion having thereon
tained across the line provided that the total
eyelets through which the leading-in conductors
length of the two lines is equal to a quarter of
extend and with which they de?ne coaxial con
a wave~length of the desired transmitted fre
ductor elements for associating the electrodes
quency.
with external coaxial conductor lines.
In known electron discharge devices, the
In accordance with one feature of this inven
lumped capacity between the electrodes and the
tion, the leading-in systems for the electrodes are
leading-in conductors therefor is very appreci
constructed and arranged so that the circuits
able. Hence, where a short-circuited coaxial line 35 within the enclosing vessel are substantially
is associated with two of the electrodes, there is
matched with the external coaxial conductor cir
placedyacross the coaxial line a lumped capacity
cuits. More particularly the leading-in systems
so that the length of the resultant circuit may
be quite short and less than the quarter wave
are of such construction that the characteristic
length requisite for the very high impedance de 40 impedance thereof is substantially the same as
the characteristic impedance of the coaxial con
sired. Even if the external coaxial line is short
ductor lines with which they are associated. The
circuited in immediate proximity to the electron
characteristic impedance may be expressed as
\discharge device, the circuit within the device
de?ned by the electrodes and the leading-in con
ductors therefor has such characteristic imped
45
I
C
'ance that the minimum operating wave-length
where L and C are the inductance and capacity
respectively, per unit length of the system or line.
; Also in electron discharge devices operable at
The characteristic impedance of the external
ultra-high frequencies, interaction between the
coaxial lines is given by the relation
input and output elements of the device presents 50
an important problem in that it a?ects materially
is relatively long.
,
the operating characteristics of the device.v
Furthermore, in such devices the dielectric
losses occurring in the seals between the electrode
Z,=.l38 Z0910 %
(1)
where Z0 is the characteristic impedance and a
and b are the diameters of the inner and outer
leading-in conductors and the enclosing vessel 55 conductors respectively. The characteristic im
2,403,444
ductors, uniformly spaced and with major sur
faces thereof in juxtaposition is given, neglecting
edge effects, by the relation
Fig. 6 is a .plan view of the structure illustrated
in Fig. 5; and
(2)
21:37? 3U1
4
of the screen ‘grid type illustrative of another
embodiment of this invention;
pedance of a line consisting of two strip-like con
where b is the spacing between the conductors
and a the width of the narrower conductor.
Such strip-like conductors may be parallel and
Figs. rI and 8 are fragmentary views showing
details of construction of the structure illus
trated in Figs. 5 and 6.
7
Referring now to the drawings, the electron
vdischarge device illustrated in Figs. 1, 2 and 3
is particularly suited for use as a grounded grid
‘ampli?er and comprises an evacuated enclosing
plane, curved or of other forms. The charactere > --10- ¥'
vessel including a substantially hemispherical
istic impedance of a line composedof ‘a strip-like ‘
conductor mounted midway between two wider
strip-like conductors of greater ‘width'is given,
neglecting edge effects, by therelation ‘
vitreous portion Ill which is hermetically sealed
“at: its edge to a ?anged metallic ring H, the
‘flange of which, is hermetically joined, as by
welding, to a metallic base plate I2. The base
plate. 'iZ-has joined thereto, four metallic eye
lets 53 through which leading-in conductors for
the electrodes of the device extend and to which
where ais the width of the intermediate conduc- ‘
tor and b is the spacing therebetween and each 20 the conductors are sealed hermetically in the
manner described in detail hereinafter.
of the two outer conductors, The conductors
Two of the leading-in conductors I 4 include
may ‘be plane and parallel, curved or of other
forms.
.
curved, ?exible, tapered strip portions 15 to
.
.In one‘ specific construction embodying the
aforenoted feature of this invention, the lead?
ing-in system for the anode. and._,control elec
trode comprises two uniformly spaced strip
members, one‘v connectedto the control electrode
and the other to the. anode, associated with the
coaxial conductor’ and "eyelet structure, the
geometry of the ‘strip members being suchthat °
the characteristic impedance of the linede?ned
thereby substantially. matches the character
istic impedanceofithe external coaxial line to
be associated .‘therewith, .The cathode-control ,
grid leading-in-syst'em includes a pair of strip~
like conductors; ‘electrically ‘integralwith the
control grid and a strip-like conductormounted
midway between these two conductors, ‘the
geometry of the several conductors being such, L
in accordance with the principles noted above,
that the characteristic impedance thereof sub
stantially matches that of the external coaxial
line portion of the cathode-control grid circuit.
which there is secured a rectilinear, ?lamentary
cathode l3 extending substantially parallel to
the base plate l2, the cathode It being main
tained under tension, to preserve the linear form
thereof, by the flexible strip portions !5, the
spring action occurring immediately adjacent the
junction of the portions l4 and I5. Encompass
ing the cathode l6 and uniformly spaced there
from is a helical control grid H which is mount
ed on a rigid metallic support l8 extending there
from and is supported in parallel relation to the
cathode i6 by a pair of plates l9 secured to the
support it, as by welding, and having flanges 28
welded to the base plate l2, and having also
flanges 2!, the purpose of which will be set forth
hereinafter.
Mounted in cooperative relation with the
cathode l6 and control grid IT is an anode, desig
nated generally by the reference numeral 22,
composed of two similar halves having joined
flanges 23, laterally extending generally tri
In accordance with another feature of this ,-, angular portions 24, and intermediate arcuate
portions 25 which together de?ne a substan
invention, shield plates are provided opposite the
tially semicircular electron receiving portion uni
ends of the electrodes and electrically integral
formly spaced from and parallel to the cathode
with the control electrode'gor grid for screening
and control grid. The laterally extending por
the leading-in system forthe cathode from the
anode.
,
>
_
In accordance with afu'rthe-r feature of this
invention, certain of the leading-in conductors
are insulated from the base plate through quartz
sleeves hermetically sealed to the eyelets through
which the leading-in conductors extend.
The invention and the above-noted and other
features thereof will be understood more clearly
and fully from the following detailed descrip
tion with, reference to the accompanying draw
ings, in which:
,
,
,
,
Fig. 1 is an elevational view mainly in section
of an ultra-high frequency electron discharge
device illustrative of one embodiment of this
tions 24 are provided at their outer ends with
sockets 23 in which leading-in conductors 21 are
secured.
Extending across the ends of the grid H are a
pair of parallel metallic shield plates 23 having
flanges 29‘ secured, as by welding, to the base
plate [2, the plates 28 being secured also to the
flanges 2| on the grid supporting plates IS. The
shield plates 28 are provided with suitable aper
tures 30 through which the ?lamentary cathode
l6 extends and, as shown in Fig. l, extend up
wardly from the base plate l2 to at least the
height of the anode ?anges 23 above the base
plate ‘and extend laterally beyond the extremities
of the anode.
>
Extending from opposite sides of the grid struc
Fig. 2 is a partial plan view of the device shown 65
ture ll, 'l8 and af?xed thereto and to the base
in Fig. 1, a portion of the enclosing vessel being
plate i2 are a pair of tapering metallic strips 3|
broken away;
,
which,'as shown clearly in Fig. 4, conform to and
Fig. 3 is an exploded view of the electrode
are spaced from the laterally extending portions
structure included. in the device shown in Figs.
2i‘: of the vanode.
1 and 2;
Each of the cathode leading-in conductors l4,
Fig. 4 is a view of the electrode structure,
l5 extends substantially midway between a pair
mainly in section along plane ll-4 of
2;
of curved strip metallic conductors 32 and 33, the
Fig. 5 is an elevational view mainly iii section
outer, 32, of which are secured to the base and
along line 5'—'-5 of Fig. Gi'of the electrode ‘and
base structure in an electron discharge device 75 shield plates l2 and 28 respectively’, and the oth
invention;
' 22,403,444
6
5
per coating on the inner surface of the quartz
sleeve and to the copper conductor or the copper
plating on the conductor. Similarly, the eyelets
may be of copper and the quartz sleeve joined
thereto through a silver sleeve which when heat
ed, as by high frequency induction in a vacuum
or heating in a hydrogen furnace, melts and fuses
to the copper eyelet and to the copper coating on
the outer surface of the quartz sleeve.
The leading-in conductor to eyelet seal may be
ers, 33, of which have their ends ‘secured to the
corresponding shield plate 28.
During operation of the device, tunable co
axial lines L, only one of which is shown, may
be associated with each of the eyelets l3 ‘and the
leading-in conductor M or 2'! extending there
through, the outer conductor of each line being
connected to the corresponding eyelet and the
inner conductor of the line being connected to
the leading-in conductor. The outer conductor
of each line is spaced from the corresponding
eyelet l3 by‘a thin insulating sleeve 80, for exam
ple of mica, so that the outer conductors are as
sociated with the respective electrodes through
blocking condensers.
It will be ‘noted that the electrodes are
mounted in close‘ proximity to the base plate [2
so that the internal circuits, of which the elec
made also by mounting the conductor, eyelet,
15
plated quartz sleeve and silver sleeves in a suitable
jig and heating the assembly in a hydrogen fur
nace and both seals, that is, quartz to eyelet and
quartz to leading-‘in conductor, made simulta- I
neously.
:
In another form, the eyelet may be silver
coated on its inner surface and the quartz sleeve
trodes and their leading-in conductors form a
silver-coated on its outersurfaoe and the two
32 and 33, which are at the same, control grid,
than that of silver itself.
part, have a relatively short physical length. 20 silver coatings sealed to one another by a silver
solder having a melting point somewhat lower
Also the shield plates 28 and the strip conductors
potential, provide a high degree of shielding be
tween the anode and the cathode and its leading
in conductors.
The portion of the control grid to anode cir
cuit within the enclosing vessel of the device
comprises in the main two spaced conductors of
‘
A conductor to eyelet seal of the construction
described provides low resistance current paths
and exhibits low dielectric losses and, hence, is
25 particularly suitable for use in ultra-high fre
quency devices.
_'
The electron discharge device illustrated in
Figs. 5, 6 and I7 is of the screen grid type and
very gradually varying width, the anode consti
tuting one conductor and the grid I1 and metal 30 suitable for grounded cathode operation. It
comprises an indirectly heated equipotential
lic members constituting the other. Hence, it
cathode including a cylindrical metallic sleeve 40
will be appreciated that the characteristic im
?tted in apertures in the shield plates 28 and
pedance of the internal grid-anode circuit may
be made substantially the same as that of the
coated on its outer surface with a thermionic ma
coaxial line associated with the grid and anode 35 terial, the sleeve enclosing a heater ?lament,
not shown, to which heating current may be sup
through the leading-in conductors 21 and the
plied through conductors 4! extending through
eyelets l3 associated therewith, whereby the por
apertures in the sleeve 40, as shown in Fig. 7, and
tions of the anode-grid circuit within and outside
through the base plate I2, the conductors M be
of the enclosing vessel are matched.
Similarly, the internal'part of the cathode-con 40 ing sealed to the base plate by insulating beads
Gil. The cathode is encompassed by a cage type
trol grid circuit, which includes the leading-in
control grid coaxial therewith, the grid compris
conductors l5 mounted between two grounded
ing a pair of metallic collars 42 fitted in aper
conductors 32 and 33 and a hybrid line section,
tures in thin insulating plates 43, for example of
i. e., between the cathode f6 and the grid [1, and
mica, secured to the shield plates 28, and a plu
is at right angles to the anode-control grid lead
rality of equally spaced parallel wires 44 se
ing-in system, may be substantially matched with
cured at their ends to the collars 42. The con
the part of the cathode-grid circuit external to
trol grid is provided at opposite ends with tap
the device.
ering, strip leading-in conductors 45 which ex
Although in both the cathode-control electrode
and anode-control electrode leading-in systems 50 tend midway between the shields 32 and 33 and
the width of the conductors and the spacing
therebetween vary, it will be appreciated that for
the lines de?ned thereby the ratio b/a, may be
maintained substantially constant so that- the
characteristic impedance of these systems may
be made substantially constant throughout the
length of the lines and substantially matched
with that of the external coaxial lines to be asso
are connected to conductors 46 joined to two of
the eyelets 13 in the manner described herein
above.
The control grid is encompassed in turn by a
screen grid which comprises a plurality of me
tallic laminations 41 apertured adjacent one end
to provide circular openings coaxial with the
control grid and maintained in parallel relation
by metallic spacers 48. The screen grid abuts
ciated therewith.
The cathode and anode leading-in conductors 60 the insulating members '43 and is seated upon a
thin insulating member 49, such as a mica plate,
i4 and 27 respectively are joined to the corre
upon the base plate l2, so that the screen grid is
sponding'eyelets l3 by insulating bodies 34 of
at radio frequency cathode or ground potential.
quartz which are sealed to the leading-in con
Direct current connection to the screen grid may
ductors and the eyelets by quantities of silver 35.
In the fabrication of the seals, coatings of cop 65 be established through a leading-in conductor 50
extending through the base plate I2 and hermeti
per are produced upon the inner and outer cylin
cally sealed thereto by an insulating head 51.
drical surfaces of a quartz sleeve, as by deposit
The anode 22 is similar to the anode in the
ing copper on these surfaces by vaporization.
device
illustrated in Figs. 1 to 4 and has its semi
The leading-in conductor, which may be of cop
per or other metal, such as Invar, copper-plated, 70 cylindrical surface de?ned by the portions 25
coaxial with the other electrodes.
is inserted into the quartz sleeve and a silver
The internal control grid-cathode circuit, it
sleeve is inserted between the quartz sleeve and
will be noted, includes two portions comprising
the conductor. The assembly is then heated, as
a strip' conductor, one of the conductors 45,
by passing a suitable current through the con
mounted
midway between a vpair of conductors 32
75
ductor, to melt the silver and fuse it to the cop
23,03,444. '
7
8
and, 33 at cathode potential so that an imped
saidmetallic portion, each of said second pair
ance match between the external coaxial and in
ternal portions of the control grid cathode cir
said ?rst metallic strips.
cult may be obtained.
v 6. An electron discharge device comprising an
of metallic strips extending between one pair of
>
. Itwill be appreciated that although the devices
shown and described are single-ended mechani
enclosing vessel having a metallic base wall, a
cathode and a grid substantially coextensive
cally, they are double-ended electrically. That
therewith, within said vessel and extending sub
is, inboth devices, the anode and cathode may be
stantially parallel to said wall, an anode, a pair
connected at opposite ends to two coaxial ex
of leading-in conductors connected to opposite
ternal circuits and the control grid and cathode 10 ends of said cathode and insulatingly sealed to
likewise may be connected at opposite ends to
said base wall, means connecting said grid elec
two external coaxial systems.
trically to said base wall, and two pairs of metal~
Although speci?cembodiments of the inven
tion have been shown and described, it will be
appreciated that they are but illustrative and
that various modi?cations may be made therein
without departing from the scope and spirit of
this invention as de?ned in the appended claims.
What is claimed is:
1. An electron discharge device comprising an
enclosing vessel, a plurality of cooperative elec
trodes within said vessel, and a leading-in sys
tem for two of said electrodes including an outer
coaxial line section and an inner section com
posed of spaced metallic strip members and hav
ing a characteristic impedance substantially the
same as that of said coaxial line section.
lic strip members electrically connected to and
extending from said Wall, each of said leading-in
conductors being positioned between one pair of
said strip members and said strip members ex
tending into proximity to the ends of said grid.
'7. An electron discharge device comprising an
enclosing vessel having a metallic bare wall, a
cathode and a grid substantially co-extensive
therewith within said vessel and extending sub
stantially parallel to said wall, an anode substan
tially coextensive with said grid, a pair of load»
ing~in conductors connected to opposite ends of
said cathode and insulatingly sealed to said base
wall, means connecting said grid electrically to
said base, wall, two pairs of metallic strip mem
2. An electron discharge device comprising an
bers electrically connected to and extending from
enclosing vessel housing a cathode, a control
electrode and an anode, and a leading~in system
for said cathode and said control electrode in»
cluding a coaxial line section, a pair of spaced
conductive strip members connected to the outer
conductor of said coaxial line section and to one
of said cathode and control electrode and a con
said wall, a pair of shields adjacent opposite end;
of said anode and electrically connected to said
ductive strip extending midway between said
spaced strips and connected to the inner conduc~
tor of said line and to the other of said cathode
strip members, each of said leading-in conduc-~
tors being positioned between one pair of said
strip members and said strip members extending
into proximity to the ends of said grid.
8. An electron discharge device comprising an
enclosing
cathode and
vessel
a grid
having
extending
a metallic
substantially
wall portion,
par
allel to said wall portion, an anode opposite said
grid, means electrically connecting said grid tov
3. An electron discharge device comprising an 40 said wall portion, a pair of metallic shields op~
enclosing vessel housing a cathode, a control elec
posite theends of said anode and extending from
trode and an anode, and a leading~in system for
said wall portion, and leading-in conductors for
said cathode extending through said shields and
said control electrode and said anode including
said wall portion and hermetically sealed to said
an outer coaxial line section and an inner section
' wall portion.
composed of metallic strips having major sur
faces. in juxtaposition, said strips being adjacent
9. An electron discharge device comprising an
and substantially coextensive.
enclosing vessel having a metallic wall, an anode
4. An electron discharge device comprising an
overlying said metallic Wall, a pair of shield plates
enclosing vessel housing a cathode, a control elec
opposite the ends of saidanode, mounted on and
trode and an anode, a leading-in system for said
electrically connected to said wall, cathode and
control electrodes adjacent said anode and
anode and control electrode including an outer
mounted between said plates, means electrically
coaxial line section and a second section com»
prising spaced conductive strip members de?n~
connecting one of said electrodes to said wall, and
ing a line having a characteristic impedance
leading~in conductors for the other of said elec
trodes extending through said shield plates and
substantially the same as that of said coaxial
line section, and a leading-in system for said
said wall.
cathode and said control electrode including an
10. An electrondiqscharge device in accordance
outer coaxial line section and a second section
with claim. 9 comprising two pairs of metallic
formed of spaced conductive strips de?ning a line
members electrically connected to said wall and:
having substantially the same characteristic
each pair extending from said Wall to one of said
shield plates on opposite sides of a corresponding
impedance as said second coaxial line section.
'one of said conductors.
5. An electron discharge device comprising an
elongated cathode electrode, a grid electrode subs
11. Anelectron discharge device comprising an
etantialy coaxial with said cathode electrode, an
enclosing vessel having a metallic wall, a cathode
anode, an enclosing vessel having a metallic por 9.5 within said Vessel andpelectrically connected ‘to
tion extending parallel to said grid and cathode
said wall, a control electrode and an anode ad
electrodes, a pair of spaced metallic strips adja~
jacent said cathode, an insulating member on the
cent each end of said cathode and grid electrodes
inner surface of said wall, and a screen grid
electrically connected to said metallic portion and
comprising a plurality of-spaced laminae seated
to one of said electrodes, and a pair of metallic 70 on said insulating member and having a portion
strips connected to opposite ends of the other
between said anode and control electrode.
of said electrodes and insulatingly sealed through
PAUL L. HARTMAN.
and control electrode.
_
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