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Патент USA US2409608

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Oct. 22,1946.
Filed Sept. 24_, 1941
' ‘2,409,603
3 Sheets-Sheet l
Fm "
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Oct. 22, 1946.
Filed Sept. 24, 1941
3 Sheets-Sheet 2
_ FIG. 3
18/ 58
Oct. 22, 1946.
Filed Sept. 24, 1941
3 Sheets-Sheet 3w
‘ F104,
Patented Oct. 22, 1946
Alva Eugene Anderson, New York, N. Y., assignor
to Bell Telephone Laboratories, Incorporated,
New York, N. Y., a corporation of New York
Application September 24, 1941, Serial No. 412,065
1 Claim. (Cl. 250—20)
This invention relates to electron beam devices,
particularly for operation at ultra-high frequen
closures or chambers 4 and 5 are associated with
An object of the invention is to intermodulate
wave energies by virtue of non-linear actions in
electron beams associated with a plurality of elec
certain electrodes within the envelope l. The
resonating chamber 4 is designated as the input
resonator and is provided with any suitable means
6 for the introduction thereinto of an incoming
electromagnetic wave.
A source ‘I of electromo
trodes, particularly for use in frequency shifting
arrangements for radio repeaters, first and sec
ond detectors in superheterodyne receiving sys
tive force of relatively low frequency is asso
ciated with one of the elements of the electron
gun 2. The resonator 5 is provided with means
tems, and the like.
10 8 for leading away therefrom developed or am
Another object is to improve and stabilize the
pli?ed energy in theform of an electromagnetic
operation of electron beam devices.
wave. The electron gun 2 is provided with an
A feature of the invention is a method of freelectron emitting cathode 9 which is associated
quency conversion employing combinations of
with any suitable heating means energized, for
velocity variation and density variation effects in 15 example, through leads I0 and II by a source l2
an electron stream with the aid of resonating
of electromotive force. Associated with the oath
ode 9 is an electrode l3 for use in regulating
A further feature is a detector making use of
and varying current of the electron beam and
a varying electron current intercepted by an
commonly known as an accelerating electrode.
apertured electrode, the amount of current inter- 20 It may be adjacent to and coaxial with the oath
cepted being varied as the result of the shifting
ode. A pair of suitably-shaped electrodes l4 and
of a focal point of a focussed electron beam.
Another feature of the invention is an auto-
[5 which may be fused into the walls of the enve
lope I, de?ne an input gap l5 and serve to close
matic volume control employing variable electron
the resonator 4 except for suitable apertures left
25 in the electrodes for the passage of an electron
Still another feature is the coupling of two
beam or stream from the gun 2. The walls of
resonators through a common wall thereof, both
the envelope I serve to separate the resonators 4
resonators being also coupled to a common elecand 5 by a desired distance and to determine a
tron beam.
suitable drift space H. A pair of electrodes l8
Further objects and features of the invention 30 and I9 de?ne an output gap 20 associated with
will be apparent from the following detailed dethe resonator 5. The resonators 4 and 5 may be
scription and the accompanying drawings, while
the scope of the invention is de?ned in the appended claim.
In the drawings,
Fig. 1 shows an arrangement for shifting from
conductively connected together and to the col
lector 3, making a system which is maintained
at a substantially constant potential difference
35 from the cathode 9 by a source 2| of electro
motive force, the negative terminal of which is
one ultra-high frequency to another, as for examconnected to the cathode. A supplemental out
ple in a radio repeater;
put means 22 is associated with the resonator 5,
Fig. 2 shows a superheterodyne receiving syspreferably in the form of a coaxial line, the inner
tern employing features of the invention in con- 40 conductor of which is connected to an interme
nection with the ?rst detector stage;
diate point 24 of the source 2! through a recti
Fig. 3 shows another form of superheterodyne
?er 23. The recti?er is shunted by a parallel
receiving system employing features of the invencombination of a resistor 25 and a condenser 26,
tion in the first and second detector stages;
the unit formed by the elements 23, 25 and 26
Fig. 4- shows an alternative form of ?rst de- 45 being serially inserted in circuit with the source
tector; and
l and the accelerating electrode IS. A stabilizing
Fig. 5 shows a detector employing a focussed
resistor 21 may be provided in the cathode lead.
electron beam with variably displaceable focal
The arrangement of Fig. l is adapted to effect
a transfer of modulated energy from one high
In the arrangement of Fig. 1 an envelope l 50 frequency wave to another, both of which may
of insulating material is shown enclosing a plube in the ultra-high frequency range. In the
rality of elements including an electron gun
operation of the system an incoming wave of the
shown generally at 2 and an electron interceptfrequency to which the resonator 4 is tuned, is
ing or collecting electrode 3 referred to- hereinintroduced through the input means 6 with the
after as the collector. A pair of resonating en- 55 consequent setting up of a high frequency alter
E5 in the input gap H6. The source ‘I is arranged
to operate at a frequency equal to the di?erence
which it is desired to introduce between the fre
quency of the incoming wave and the frequency
with the steady biasing potential impressed
upon the accelerating electrode H3. The circuit
is so arranged that the potential difference across
the resistor 25 opposes the potential of the
source 2i in determining the resultant potential
of the electrode l3. In the well-known manner
of automatic control systems of this type,
changes in the amplitude of the output wave
of the outgoing wave. The resonator 5 is tuned
to the frequency of the outgoing wave. The
function of the source ‘I’ is to superpose variations
of the above-mentioned difference frequency
upon the potential of the electron accelerating
due to variations of the input wave are mini
electrode :3 to regulate the space charge effect
in the tube and consequently to produce corre
sponding variations in the current or electron
density of the beam. The beam, in traversing
the input gap i5, has superimposed upon the
above-mentioned current variations from source
‘I, a succession of electron velocity variations
impressed by the incoming wave. It is further
contemplated that the incoming wave will carry
amplitude modulations corresponding to a signal
If it is desired, instead, to emphasize
amplitude changes to secure a volume expansion
effect, the polarity of the recti?er 23 may be
made the reverse of that shown.
Stabilization of the system against power sup;
which is to be repeated. . The electron beam,
thus modulated in density in accordance with
the oscillations of the local source ‘I and in
‘velocity in accordance with the variations of the
incoming wave, is allowed to traverse the sub
ing slow changes of current to produce a varying
potential difference across the elements in series
nating potential between the electrodes M and
ply fluctuations associated with the source 21 is
provided by means of the resistor 27 in the
cathode return lead. Changes in the cathode
return current affect the potential difference
across theresistor 2T inherently in the proper
sense to minimize such current changes by con
trolling the effective voltage between the cathode
on the one hand and the system comprising the
resonators 4 and 5, collector 3, and associated
electrodes on the other hand.
stantially ?eld-free drift space H to permit
Arrangements for maintaining an electron
further grouping of the electrons to take place.
beam in any other suitable manner may be
In the absence of the density variations im
substituted for the electron gun 2. Any suitable
pressed upon the electron beam by the source l
but in the presence of velocity varying poten 30 resonators and electrodes may be substituted for
the corresponding elements illustrated provided
tials across the gap N5, the velocity variations
tend to produce approm'mately proportional elec
tron density variations at the output gap 26.
‘The effect of the superposed density variation
in the beam current is to produce a variation
in the number of electrons per unit time which
are subjected to the velocity variation at the
input gap. As a result, the electron density
variation at the output gap 26 tends to be pro
'portional to the product of the two superposed
variations, thereby introducing components cor
responding tointermodulation products, such as
combination frequencies according to well-known
principles. Any desired modulation product may
be accentuated by dimensioning or tuning the
resonator 5 to resonate at the frequency of the
selected modulation product. For example, the
component of frequency equal to the incoming
only that means are present for superposing an
amplitude or current density variation and an
electron velocity variation upon an electron beam
which beam is thereafter subjected to suitable
conditions or manipulation which results in a
regrouping of the electrical charges in the beam
in some manner adapted to produce intermodu
lation of the original variations. The automatic
control features and stabilizing elements may,
of course, be either omitted or included, as
Fig. 2 illustrates certain features of the inven
tion embodied in a superheterodyne radio re
ceiver. The facilities for producing the electron
beam, the envelope l, the collector 3, and the
input and output resonators and associated ar
rangements are substantially the same as in the
frequency minus the frequency of source ‘I may
system of Fig. 1, except that the output resonator
be selected ‘by making the critical dimensions of
the resonator 5 somewhat greater than those of
the, resonator 6 in such proportion as to tune the
resonator 5 to the desired output frequency.
resonator 4. Intermediate between the input and
output resonators are two auxiliary chambers 28
With proper tuning, an electromagnetic wave
5' is tuned to the same frequency as the input
and 29 having a common wall 39. The interiors
of the chambers are shown coupled by means of
of the selected frequency will be sustained in 55 a coupling loop 3| passing through an aperture
the resonator 5 and delivered to the ouput means
3. By making the resonator 5 somewhat smaller
than the resonator ll, on the other hand, the fre
quency component equal to the incoming fre
in the Wall 3!}. Alternatively, the loop 3| may be
omitted and the aperture itself may be suitably
provided between the resonators 6i and 28 and the
resonators 29 and 5’. Electromagnetic focussing
coils 38 and 39, respectively, may conveniently
be, placed. adjacent to the drift spaces 36 and 31
and energized by sources 45) and iii of electromo
dimensioned to provide the coupling. If desired,
an iris or other suitable arrangement may be used
quency plus the frequency of source ‘I may be 60 to secure a variable coupling. Conductively con
nected with‘ the wall 30 is an electrode 32 com
selected. Of particular interest in the use of the
prising adisc with an axial aperture surrounded
arrangement of Fig. 1 as a radio repeater, the
by a short tube 33. The resonators 28 and 29 are
diiference between the input and output fre
provided with electrodes 34 and 35 respectively
quencies is utilized to avoid undesirable reaction
of the output upon the input which would other 65 having apertures aligned with the aperture in the
disc 32. Drift spaces 36 and 31 respectively are
wise cause self-oscillations or f‘singing” in the
Automatic stabilization of the intensity of the
output wave is provided by taking a sample of
the output wave from the resonator 5 through
the coupling means 22 and applying the sample
wave to the rectifier 23. The time constant of
the resistor-condenser combination 25, 26 is
preferably adjusted to a suitable value to smooth
out rapid variations of the recti?ed current, leav
tiverforce. Alternatively, suitably designed per
‘manent magnets may be substituted for the elec
‘tromagnets. The collector 3 is connected by way
75 of a tuned circuit 42 to the cathode 9. An inter
The system of Fig. 2‘ may be employed simply
mediate frequency ampli?er 43, a detector 44 and
as a high frequency ampli?er if desired, in which
case, the high frequency output may be taken
from the resonator 5' by any suitable output
means such as the coupling 8 illustrated in Fig. 1
and the collector may be connected to the posi
tive terminal of the source of biasing potential.
Elements 42, 43, M and 45 and source ‘5 may then
a translating device 155, such as a telephone re
ceiver, are coupled in tandem arrangement with
respect to the tuned circuit 132 in the conventional
manner of a superheterodyne receiving system.
The control elements 23, 25 and 26 may be coupled
to the output device 22 in a manner similar to
that shown in Fig. 1. In this case, however, the
control is shown applied to the potential of the
resonating system instead of the electron accel
erating electrode.
The operation of the system of Fig. 2 in its
\be omitted.
The automatic control arrangement‘of Fig, 2
is shown as operating to control the average
electron velocity at the electrode i4 thereby con
trolling the electron transit time through the drift
spaces 35 and 3‘! and consequently controlling
broad aspect is similar to that of any super
heterodyne receiver. An input wave is impressed
upon the resonator it through the input coupling 15 the gain of the device as a high frequency am
pli?er. With the recti?er 28 polarized in the di
6 to impress velocity variations upon the electron
rection indicated by the arrow the control is such
stream which has also been given an electron
as to minimize volume changes. If instead, it is
density variation through the action of the local
desired to emphasize the volume changes to give
source ‘i. The operation of the system differs
a volume expansion effect, the polarity of the
from that of Fig. 1 among other particulars, in
recti?er should be reversed.
that the essential interrnodulation of the local
Fig. 3 shows a superheterodyne receiving sys
and incoming waves is effected in a somewhat
tem employing two electron beam devices in a
different manner. Intermodulation according to
tandem arrangement. In the ?rst tube, shown
the scheme described in connection with Fig. 1
at the top of the ?gure, the incoming wave is
may also occur in the drift space 36 of Fig. 2, but
impressed upon the resonator G by means of the
by tuning the resonator 28 to the frequency of
coupling 5 to produce a velocity variation in the
the incoming wave the intermodulation at this
electron beam at the gap :6. Conversion of the
point may be subordinated to ampli?cation of
velocity variations into current density variations
the incoming wave, the latter process being
is provided for in the drift space ll. The local
brought about by electron density variations serv
oscillations are generated in a resonant chamber
ing to set up forced oscillations in the resonator
of concentric structure having an outer wall 50,
28. A portion of the energy of these oscillations
and inner walls 5!, 52, 53 and M, of which 52 and
is transmitted to the resonator 29 by means of a
53 are conductively connected with the outer wall
coupling loop 3! to produce a second and rela
tively intense velocity variation of the electron I by wires 88 and 38, respectively. The wires are
preferably of su?iciently small dimensions not to
beam in the gap between electrodes 33 and 35.
interfere materially with the transmission or os
By electron drift action in the drift space 3? a
cillation of electromagnetic waves within the en
further ampli?ed electron density variation is
closure. The wires preferably extend radially or
produced in the gap 28, causing forced oscilla
tions in the resonator 5’. The ampli?ed oscilla 40 substantially perpendicular to the electrical lines
of force normally existing therein. Three gaps
tions in the resonator 5’ will impress a new and
55, '56 and 57 are provided along the course of
still further ampli?ed velocity variation upon the
the electron beam separated by additional drift
electron beam before the beam enters the space
spaces 58 and 59. The electrode I851 together with
between the electrode Iii and collector 3.
To obtain the desired intermediate frequency 4 an electrode I8! de?nes the gap 55 and the gaps
'55 and 57 are de?ned by similar pairs of elec
component which may be at the frequency of the
trodes. The ends of the resonating chamber are
difference between the incoming wave and the
closed by means of annular pistons 6t and SI,
source if, velocity sorting of the electrons is ef
which are slidable for purposes of tuning the
resonant chamber. The collector 3 is conduc
tively connected to the inner conductor 6!! of a
concentric transmission line of which a tube '65
fected by subjecting the beam to a retarding or
re?ecting ?eld. The ?eld is conveniently pro
duced by connecting the collector 3 to the cathode
9 as illustrated, thereby placing the collector 3
at a potential considerably negative with respect
to the potential of the electrode l9. Due to the
reflecting ?eld, the slower electrons passing elec
of conductive material connected conductiv'ely
with the walls of the resonanting chamber is the
outer conductor. The conductor 6!! is connected
to the tuning chamber and to ground through
a high frequency choke coil 86. The concentric
line 64, 65 is connected to another concentric line
trode it are unable to reach the collector 3 and
are turned back, but the faster electrons are able
to enter the collector 3 and induce a pulsating
current in the return circuit. The intermediate
68 of smaller diameter through a tapering sec
tion 67.
frequency component of the pulsating current is
resonated by the tuned circuit 42, thereby supply
ing an input to the intermediate frequency ampli
?er @3. Intermediate frequency ampli?cation and
a A second electron beam tube serving as an am
?nal detection as well as translation of the signal
‘ are accomplished in the usual manner as in any
superheterodyne receiving system.
It is contemplated that the frequency of source
pli?er and second detector is shown in the lower
portion of the ?gure and has an input resonator
82 coupled to the transmission line 68 by means
of a coupling loop 69 inside the resonator. The
wave impressed upon the resonator 62 produces a
velocity variation of the electron beam at an
input gap ll]. Velocity sorting is effected in the
‘I will be relatively low compared to the frequency
output gap ‘ll due to the steady difference of
of the wave incoming at the coupling 6, in which
maintained between insulated portions
case the difference frequency will lie within the
82 and '83 of an output resonator by the electro
transmission band of the resonators ll, 23, 29 and
mctive force of a biasing‘source 84. The slower
5’. If desired the transmission band may be
electrons of the beam are turned back and only
widened by detuning slightly one or more of the
the faster electrons continue, ?nally striking a
resonators or by increasing the degree of cou
75 collector 12. A coupling transformer 13 is pro
pling between resonators 28 and 29.
vided for repeating the alternating portion of the
used instead of the connected electrodes I03 and
pulsating current in the collector lead and a
translating device such as a telephone receiver 14
is connected to the secondary of the‘ trans
former ‘I3.
In the operation of the system of Fig. 3 the in
coming oscillations and local oscillations are com
bined in the ?rst or upper tube to produce a wave
I04. Focusslng means such as an eleotromagnet
I01 energized in any suitable way as for ex
ample by a battery I08 is provided to bring the
electron beam to a focus near the electrodes I03
and I04.
In the operation of the system of Fig. 5 the
incoming wave is resonated in the chamber I00
of somewhat lower frequency corresponding to
and by means of the gap IOI impresses a velocity
the usual “intermediate frequency” wave. The 10 variation upon the electron beam. The electron
wave so produced is ampli?ed by the second or
gun 2 is preferably of a type which focusses or
lower tube and the signals are detected by the
concentrates the electron beam, and arranged to
velocity sorting process above described. The
establish a focal point in the gap I M. The
local oscillator is substantially a, two-stage am
focussing coil I01 normally produces a point of
pli?er with coupling between the output and in 15 concentration of the beam in the neighborhood
put. The relative voltages impressed upon the
of the electrodes I03 and I04. The electron
input gap 55 and the output gap 51 may be ad
velocity variation impressed upon the beam is
justed by proper setting of the tuning pistons 60
arranged'to be su?icient to cause a shifting of
and BI, a movement of both pistons in thesame
the point of concentration axially with respect to
direction an equal amount having substantially 20 the electrodes I03 and I04 in accordance with
no effect on the resonant frequency. I If it is de
amplitude modulations of the incoming wave.
sired to operate the lower tube at a much lower
The electrodes I03 and I04 are thus caused to
frequency, e. g. in the ordinary intermediate fre
intercept a variable portion of the electrons of
quency range, the second tube may be replaced
the beam, thereby producing a pulsating current
by a conventional intermediate frequency am
through the resistor I 005 and receiver I06. If
desired, the resistor I 05 may be replaced by a
Fig. 4 shows another arrangement for the ?rst
tuned circuit resonant to a desired intermediate
detector of a superheterodyne receiving system.
frequency and the voltage variations in this
A resonant chamber 90 is tuned to the incoming
tuned circuit may be employed to excite an in
frequency. Another resonant chamber SI having : termediate frequency ampli?er.
a wall in common with the resonator 90 is tuned
What is claimed is:
to the frequency desired for the local or beating
A modulating system comprising an electron
oscillator. A gap 92 is provided within the reso
beam-type tube, a plurality of resonating cham
nator 90 and gaps 93 and 04 within the resonator
bers arranged in succession along the path of
0|. The collector 3 is connected to the biasing
the electron beam, one of said resonating cham
potential source through a tuned circuit 05 which
bers having two electron permeable electrode
may be tuned to the difference frequency.
portions in opposite walls, in alignment with the
In the operation of the arrangement of Fig.
electron beam to permit the beam to traverse
4 the electron beam receives a velocity variation
said resonating chamber, another of said reso
in accordance with the incoming waves at the 40 nating chambers being located beyond said ?rst
gap 92. The beam receives a second electron
mentioned resonating chamber and enclosing a
velocity variation at the gap 93 in accordance
drift tube and having two electron permeable
with the local oscillations. The electron path
electrode portions in opposite walls, said elec
between the gap 93 and the collector 3 is essen
trode portions and the axis of said drift tube
tially a drift space and due to the non-linear
being in alignment with the electron beam, said
character of the drift space action, difference fre
> second-mentioned
resonating chamber being
quency components are set up in the electron
resonant at a frequency di?erent from the
density variations e?ected by the drifting of
resonant frequency of the ?rst-mentioned reso
the electrons. The gap 94 is provided for the
nating chamber, a source of electroenagnetic
purpose of extracting enough energy from the
waves coupled to said ?rst-mentioned resonat
electron stream to support continuous oscilla
ing chamber to excite forced oscillations there
tions in the resonator 0%. The intermediate fre
in and to impress an electron velocity variation
quency wave may be of sufficiently low frequency
upon the electron beam at the frequency of said
to be handled with ordinary tuned circuits, and
forced oscillations as the beam traverses the
any desired utilization device, such as an inter
resonating chamber, a substantially ?eld-free
mediate frequency. ampli?er, may be coupled to
drift space between said ?rst and second-men
the tuned circuit '95 in well-known manner.
tioned resonating chambers for converting the
Fig. 5 shows an alternative form of detector
said velocity variation of the electron beam into
which may be used either as a ?rst or second
a corresponding electron density variation, means
detector in a superheterodyne receiving, system
including the said electron permeable electrode
or as a simple detector for the direct conversion
portions of said second-mentioned resonating
of an ultra-high frequency wave to recover the
chamber and the said drift tube enclosed within
original signals in a single step of detection. A
said resonating chamber for generating self
resonator I00 is provided for the input wave
oscillations in said second mentioned resonating
and is associated with a gap IOI. Separated
chamber and for impressing upon the said density
from the ?rst gap by a space I02 are a pair of
varied electron beam at a point ahead of said
connected electrodes I03 and ‘ E04, which may be
enclosed drift tube, a second velocity variation at
like the electrodes shown herein for the accom
the frequency of said self-oscillations and means
modation of a resonating chamber, but with the
including the said enclosed drift tube for con
chamber omitted. The electrodes I03 and I04 70 verting the compound variation of the electron
are connected to the positive terminal of the
beam so produced into a second electron density
biasing potential source through a resistor I05
variation comprising an intermodulation of said
which is shunted by a translating device such
forced oscillations and said self-oscillations.
as a telephone receiver I06. A single electron
permeable electrode of any suitable type may be 75
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