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Патент USA US2410841

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Patented Nov. 12, 1946
Arthur L. Samuel, Summit, N. 3., assignor to
Bell Telephone Laboratories, Incorporated, New
York, N. Y., a corporation of New York
Original application May 6, 1942, Serial No.
441,937. Divided and this application October
19, 1942, Serial No. 462,537
1 Claim. (01. 178—44)
This invention relates to electronic devices, par
ticularly for operation at ultra-high frequencies.
the electron stream as hereinafter described, and
each is provided with a central aperture in align
ment with the axis of the electron gun 2 in order
to accommodate the passage of the electron
stream from said gun to the collector 3. A pair
An object of the invention is to facilitate the
operation and tuning of ampli?ers, oscillators and
the like, especially those employing resonating
of adjacent discs 2“ and M2, respectively, ‘form
chambers or cavity resonators.
A feature of the invention is a provision for a
precise or ?ne adjustment of the tuning of a cav
ity resonator comprising an adjustable branch
parts of opposing walls of ,an input resonator I20.
The disc 2II may have attached thereto a short
tube 2 I 8 aligned with the aperture and extending
chamber of such restricted dimensions compared 10 outwardly with respect to'the walls of the reso
nator I20. The disc ‘2! 2 has fastened to the edge
with the main cavity that the resonant frequency
of the aperture therein a relatively long, ?aring
of the main cavity is close to and somewhat below
tube I22. Longitudinally of "the path of the elec
the range of free transmission of electromagnetic
tron stream a gap I2I is de?ned between the cen
waves in the branch cavity so that the latter will
not fully support a wave of the frequency to be 15 tral portion of the inner surface of the‘ disc 2H
and the small end of the tube I22. The disc 2I3
resonated and adjustment of the size or shape of
has fastened to the edge of the aperture therein
the branch cavity will have a de?nite but rela
a ring-shaped electrode I 24 positioned adjacent
tively small effect upon the resonance of the ar
to the large end of the tube I22. An annular
rangement as a whole.
Another feature of the invention is the provi 20 gap I23 is de?ned between the adjacent ends of
the tube I22 and the electrode I22. A pair of ad—
sion of a plurality of loosely coupled branch ~cav_
jacent discs 2M and 2~I5, respectively, form parts
ities adjustable to resonate at the same fre
of opposing walls of an- intermediate resonator
quency as the main cavity or at slightly di-iferent
I 23. The disc 2M supports a ?aring tube I26
frequencies, producing in either case a broad fre
quency band or relatively flat transmission char 25 similar to but inverted with respect to the tube
I22 with the large 'end of the tube I26 de?ning
acteristic for the system.
together with the upper edge of the electrode I24
an annular gap I25. The disc 2-I5 may have, at
tached to its outer side and surrounding the
a division of my copending application, Serial No. 30 aperture, a short tube 2H. A gap .I2'I is de?ned
This application includes subject-matter orig
inally disclosed in my copending application, Se
rial No. 412,067, ?led September 24, 1941, and is
between the central portoin of the inner surface
of the disc 2!?) and the small end of the tube
441,937, ?led May 6, 1942.
Further objects and ‘features of the invention
will be apparent from the following detailed de
The walls of the resonator I22 should be con
scription and the accompanying drawing, while
the scope of the invention is de?ned in the ap
35 ductive, or should at least have conductive inner
surfaces. The tubes I22, I25, 2I8 and 2I9 and
the ring I24 should be conductive and should be
conductively fastened to their respective support
embodiment of the invention in a frequency con
ing discs.
version system employing resonating chambers or
The portion of the arrangement so far de
cavity resonators.
scribed is similar to one disclosed and claimed in
Referring to the drawing, an evacuated, insu
my copending application, Serial No. 388,031, ?led
lating envelope I is represented as enclosing a
April 11, 1941, and assigned to the assignee of
plurality of elements including a suitable source
the present application. The resonator I20 may
of an electron stream such as an electron gun or
beam projector shown generally at 2,-and an elec 45 be connected with a suitable wave guide for sup
plying incoming waves to the resonant system,
tron intercepting elctrode or collector 3. The
the guide being separated from the resonant
electron gun 2 is provided with an electron emit
pended claim.
The single ?gure of the drawing represents an
chamber by a conductive partition I6 I. . Coupling
ting cathode 9 which may be associated with any
between the guide and the resonant chamber may
suitable heating means energized, in the embodi
ment illustrated, through leads I0 and II by a 50 be effected by means of a suitable aperture I62
in the partition I6I. The wave guide may be
source I2 of electromotive force. Associated with
formed as an extension of the Walls of the reso
the cathode '9 there may be an electrode I3 for
nator I2? as shown.
use in regulating and varying the current of
Separated from the gap I21 by a suitable drift
the electron beam and commonly known as an ac
celerating electrode. It may be adjacent to and 55 space I29 is a gap I30 which is de?ned by op
coaxial with the cathode.
A plurality of conductive discs H I to 2I'I, in—.
elusive, are hermetically sealed into and through
the envelope I in any known manner. The discs
are spaced at suitable intervals along the path of 60
posed truncated conical portions of the discs 2I6
and 2H. These discs form portions of the walls
of a resonator, e. g., a quarter wave-length co
axial conductor system 2E8, which may have a
tuning branch 209.
A source It!) of alternat
ing potentials is connected with the electrode I24, 4
shown a precise or ?ne tuning arrangement, com
the direct potential of electrode I24 being main
prising a branch cavity 202 of relatively small
tained at a relatively low potential with respect
dimensions, shown broken open, in which is slid
to the cathode by a source I4I, whereas the con
ably mounted a piston I53 which may be moved
ductice portions of the resonators I20, I28 and 208 5 by means of a suitably connected knob I54. A
and the collector 3 are maintained at a relatively
similar arrangement may be employed in con
high positive potential with respect to the cath
nection with the resonator I20. The branch
ode by means of batteries 200 and 20I. The elec
cavity 202 is preferably of such restricted dimen
sions compared with the‘ main cavity that the
trode I3 may be connected, as shown, to the
positive terminal of the battery 200. To effect
resonant frequency of the main cavity is close to
the relative potential values hereinbefore speci
and somewhat below the range of free transmis
?ed the potential of the battery I4I may be
sion of the branch cavity so that the latter will
relatively low with respect to the combined po
not fully support a wave of the frequency to be
tential of batteries 200 and 20I. The tuning
resonated. Then a relatively large motion of the
branch 209 may serve to de?ne the short-cir 15 piston I53 will produce only a relatively small
change in the resonant frequency of the combi
cuited end or voltage node of the quarter wave
length line 208, another branch 2I0 being pro
nation. The currents ?owing in the branch cav
vided for connection to any suitable load.
ity will be less than in the main cavity with the
In the operation of the system shown in the
result that any losses associated with the slid
drawing, the input wave, the carrier frequency 20 ing contacts between the piston I53 and the walls
of the cavity 202 will be minimized.
of which will be designated f1 and which wave
The resonator I20 is provided with adjustable
may bear signals in the form of modulations,
side cavities 203 and 204 for the purpose of en
e. g., amplitude modulations, is resonated in the
chamber I20 and produces an electron velocity
abling the resonator to respond to a relatively
variation in the electron stream as the latter
wide frequency band. The side cavity 203 is
traverses the associated gap I2I. The frequency
coupled to the main cavity by means of an aper
ture 205 and is adjustable by means of a piston
of the wave supplied by the local source I40 will
be designated f2. Electron velocity sorting takes
206 connected to a knob 201. The side cavity 204
is connected to the main cavity and adjustable in
place within the tube I22 due to the influence of
the relatively low potential of the electrode I24. 30 a similar manner. The resonator I28 may be
With proper selection or adjustment of the bat
similarly equipped. The aperture 205 is prefer
tery potentials, a condition is readily secured
ably of a suitable size to provide a loose coupling
in which the faster electrons pass through the
between the adjacent chambers. The side cav
space within the electrodes I24 and I26 whereas
ities may be independently adjusted to resonate
the slower electrons are de?ected and intercepted
at the same frequency as the associated main cav
ity or at slightly different frequencies, producing
by the electrodes I22, I24 and I26, the result
being a charge density variation both in the
in either case a broad frequency band or rela
stream of electrons which pass beyond the tube
tively ?at transmission characteristic in the well
I25 and in the current intercepted by the elec
known manner of coupled resonant circuits of
trodes. The degree of velocity sorting and re 40 Whatever form.
sultant grouping produced is, however, in the
In the operation of the system as above de
present system, under the control of the local
scribed the resonator I20 is assumed broadly
source I40 by virtue of the variable potential
tuned to the'frequency ii of the incoming wave
superimposed upon the direct current biasing po
and responsive to the sidebands due to the modu
tential of the electrode I24 which causes the re- '
sultant, bias to ?uctuate. Upon passing the gap
I21, the density-varied electron stream serves
to excite electromagnetic oscillations in the reso
nator I28, which resonator may be tuned to re
frequencies ‘
(f1+f2) and (ii-f2), to reinforce these frequen
cies which, it will be noted, are modulation prod
ucts separated from the frequency of resonator
I20 by an amount equal to the value of the fre
quency of the source I40.
Oscillations thus pr'o- ’
duced in ‘resonator I28 impress a corresponding
velocity variation upon the electron stream as the
latter traverses the gap I21. The velocity varia
tion of the electron stream entering the drift
space I29 will contain a component of the local
lation which the incoming wave may bear. The
resonator I28 may be tuned broadly to (f1+f2) or
(f1—f2) as desired, while the line 208 is tuned to is.
It is also feasible to operate by tuning the res
onator I28 sharply to one of the above-mentioned
frequencies. In that case, the side chambers
203’ and 204' are not needed and the apertures
for coupling the side chambers to the main cavity
should be closed. It is also feasible to operate
with the resonator I 28 tuned so broadly as to
include both (f1+f2) and (fi-fz), in which case
the line 208 may be energized at twice the fre
quency f2 and the length of the line 208 up to
the position of the tuning stub should be increased
What is claimed is:
A tuning arrangement comprising a substan
tially closed system of resonating chambers con
frequency is of source I 40 bearing the signal
modulations of the original incoming Wave of
frequency ii. The velocity variation is con
taining a main chamber and a communicating
verted in the drift space I29 into density varia
branch chamber, said branch chamber being of
tions at the gap I30 by the grouping effect of ' : restricted
faster electrons overtaking slower electrons.
The resonant line 208 may be tuned by means
of the adjustable branch 209 to the frequency is
of the source I40 and will be excited into forced
oscillations by means of the density variations
at the gap I30. The output of the line 208 may
be led through the branch 2I0 to a suitable load
such as an intermediate frequency ampli?er or
other utilization means.
In connection with the resonator [28 there is
dimensions to determine for said
branch chamber a cut-off frequency close to and
somewhat above the resonant frequency of the
main chamber, whereby a Wave impressed upon
said main chamber and substantially resonant
therein is attenuated upon entering said branch
chamber, and means for tuning said branch
chamber to effect a ?ne tuning adjustment of the
system as a whole. -
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