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Патент USA US2121737

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June 21‘, 1938.
c, w_ HANSELL
2,121,737
VARIABLE REACTANCE MODULATOR CIRCUIT
Filed July 24, 1933
4 Sheets-Sheet l
INVENTOR~
CLARENCE W. HANSELL
ATTORNEY
June 21, 1938.
c. w. HANSELL
2,121,737
VARIABLE REACTANCE MODULATOR CIRCUIT
Filed July 24, 1955
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INVENTOR
a I QIT'ARENCE W. HANSELL
ATTORNEY
June 21, 1938.
2,121,737
C. W. HANSELL
VARIABLE REACTANCE MODULATOR CIRCUIT
Filed July 24, 195-3
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INVENTOR
8
CLARENCE W.HANSELL
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BY
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ATTORNEY
Patented June 21, 1938
UNET
2,121,737
SATS
2,121,737
VARIABLE REACT’ANCE MODULATOR CIR
~
CUIT
Clarence W. Hansell, Port Jefferson, N. Y., as
signor to Radio Corporation of America, a cor
poration of Delaware
Application July 24, 1933, Serial No. 681,945
7 Claims. (Cl. 179-—171)
This invention relates to circuits, such as used
electron emitting cathode in the absence and in
in phase modulation apparatus, whose reactance
may ‘be rapidly varied. More particularly, my
present invention relates to variable condensers
the presence of electric or magnetic ?elds or
both;
Figure 6 diagrammatically indicates a system
utilizing a circuit whose capacitive reactance is
"'5 of a type whose reactance may be varied from
relatively low frequencies up to a rate corre
varied rapidly by means of one form of my im
proved magnetically controlled electron con
denser having two electrodes;
Figure ’7 illustrates a modi?cation wherein the
distribution of electrons is effected by a magnetic 10
?eld and rapidly varied in accordance with modu
lating potentials applied to one or more auxiliary
sponding to frequencies of millions of cycles per
second.
Such condensers are particularly useful
as already indicated, to produce phase and often
'10 times frequency modulation of ultra high fre
quency transmitters, especially those which re
quire high frequency modulation such as, for ex‘
ample, a television transmitter. They also may
be used in some systems for producing amplitude
15 modulation.
It has been proposed heretofore, in order to
provide a condenser whose reactance may rapidly
be varied, to change the ionization of vapor
molecules within thedielectric between a pair of
.20 electrodes mount-ed within an hermetically sealed
electrodes;
Figure 8 illustrates, in wiring diagram form, a
system utilizing an electronic condenser whose
capacity or electronic‘ distribution is controlled
purely electrostatically; and,
Figure 9 illustrates a system wherein capacity
variation is accomplished by the combined action
of magnetic and electric ?elds, or in the alterna
tive by either alone.
Turning speci?cally to the drawings, Figures
characteristic and is subject to temperature and
other variations. It is also limited in the maxi
mum rate or frequency at which its capacity may
be varied due, to the relatively slow rate of change
of ionization of the gas with changes in control
electron discharge device having‘ an electron
emitting cathode 2 and a relatively cold electrode 25
4 spaced concentrically from the electron emit
currents or potentials.
have been omitted from the ?gures for the sake
1 to 3 inclusive indicate cross sections of an
ting cathode.
To provide a condenser
which is free of those disadvantages, is the prin
of simplicity.
tained within an hermetically sealed container
at least one of the electrodes being made in the
form of an electron emitter such as the cathode
‘
Now, if the electron emitting cathode 2, of
Figure 1, is heated to incandescence or otherwise 35
arranged to emit electrons and assuming a rela
of an electron discharge device. Brie?y, I con
trol the distribution or location of electrons about
tively positive potential applied to the relatively
the cathode electrode with respect to another as
sociated electrode electromagnetically, electro
statically, or by the combined action of magnetic
and electrostatic ?elds. The presence of free
electrons in a space subjected to alternating cur
rent ?elds changes the effective dielectric con
stant and magnetic permeability of a space and
variations in the electron positions or density
varies the capacity and permeability.
Obviously, the glass containers
In Figures 4 and 5 there is placed between the 30
electron emitting cathode 2 and cold electron
receiving anode 4, a further concentric control or
cold electrode 6.
.30 cipal object of my present invention and to do so
I vary the distribution of electrons or clouds of
electrons in the space between electrodes con
i 35
20
container. Such a variable gas system suffers
from the disadvantages that it has a non-linear
cold electrode 4, electrons will be attracted to the
anode or cold electrode 4 as illustrated by the
dotted arrowed lines. Obviously, this action takes .
place over each in?nitesimal area on the cathode
so that there is effectively a cloud like flow of
electrons from the cathode 2 to the anode 4 in the
direction of the arrows.
As an electron represents a change in motion, 45
This ' application of a magnetic ?eld thereto will cause
.
it to become deflected. Thus, by applying a suf
My present invention will be described in
?ciently strong magnetic ?eld, to the space be
phenomena is used in my invention.
greater detail in connection with the accom
'50 panying drawings which, it is to be clearly under
stood, are merely illustrative of it and are not to
be considered in any way limitative. Turning
to them,
Figures 1 to 5 inclusive indicate the electronic
?ow or distribution or both of electrons about an
tween the cathode 2 and anode 4 of Figure 1, in
a direction normal or perpendicular to the paths 50
of the electrons, clouds of electrons, or any par
ticular ?nite number of electrons, are made to
travel in curved paths such as illustrated in
Figure 2. That is to say, by applying a magnetic
?eld of sufficient strength to the space traversed
2
2,121,737
by the electrons, such that the lines of mag
netic flux are coaxial with or parallel to the
linear or cylindrical ?lament 2, the electron paths
become curved. With increasing strength of
magnetic ?eld the electrons will be caused to
return substantially to the ?lament, or looked
at in a little different light, may be so curved that
no electrons strike the anode and the flow of so
called anode current ceases. Figure 3 illustrates
10 the concentrating electron effect of increased
strength of magnetic ?eld.
The “crowding" ef
fect of electrons about the cathode may also be
ing condensers 28, 30. The modulator tubes are
also provided with ?laments or electron emitting
cathodes 32, 34 whose heating circuits have been
omitted for the sake of simplicity. The ?laments
may be grounded as illustrated. About the tubes
24, 26 is wrapped a’solenoid or magnetic ?eld
coil 36 whose energization from source 38 is ad
justed to a desired value by means of variable
resistor or potentiometer 40.' The coil 36 is shown
diagrammatically but it will be understood that 10
in practice this coil is so arranged relative to the
tubes that its magnetic ?eld is perpendicular to V
varied with variations in potential applied to the flow of the electrons from the tube’s cathodes
anode 4.
.to the tube’s anodes. Of course, separate ?eld
By causing the electrons to described curves of coils for each tube may also be used and iron may 15
16
various radii either by variation in plate potential be employed in the magnetic circuit outside the
or by variation in magnetic ?eld strength, or by tubes to reduce the number of ampere turns re
variation of both, the density and paths of elec
quired in the coil. Modulation potentials are
trons in the space between the cold electrode
applied to the cold electrodes 26, 22 through the
20 and cathode is varied. Because of the fluctua
input transformer 42, which in turn causes varia 20
tions in electronic positioning and density with tion in distribution of electrons between the oath
respect to the anode, the effective dielectric ca
odes and plates of the modulator tubes. In this
pacity of the space between the anode and cath
manner a portion of the output circuit 14 is par
ode varies.
Stated a little differently, over a
considerable range of anode cathode voltage var
iation, with a given value of magnetic ?eld, no
anode current ?ows but the average density and
space distribution of‘ electrons within the tube
changes. The change in density and distribution
30 of electron charge around the cathode varies the
allel with a variable condenser as described here
inabove, as a result of which the frequency of 25
oscillations generated by the tubes 8, I 0 is var
ied.
If desired, tubes 8, 10 may be adjusted as re
gards voltage and circuits so that it acts as an
ampli?er in which case input energy of high fre i 30
effective cathode diameter so far as dielectric ca
quency may be applied to the input circuit l2.
pacity and reactance for radio frequency cur
rents are concerned. This reactance, of course,
The modulator tubes would then be operated un
der the same condition as before, namely, that a
?eld is applied having a strength greater than
can be varied as will be described more fully
35 hereinafter with variations in plate potential or
that required to produce cut off, and in that :35
magnetic ?eld strength or both.
. event, the resultant energy fed to the output cir
As an additional control, further electrodes
cuits l6, l8 will be phase modulated in accord
may be interposed between the cathode 2 and ance with the modulation frequency input ap
cold electrode 4 as shown in Figure 4 wherein the
plied through transformer 42. The high fre
'40 cross-section of a control grid or control elec quency source coupled to the input circuit l2 in 40
trode 6 has been illustrated. Variations in po—
this case may be, for example, any of the high
tential applied to this control electrode will also frequency sources described by Nils E. Lindenblad
vary electronic distribution and hence affect the in his copending applications referred to above.
capacity between the cathode 2 and cold elec
It should also be noted that instead of feeding
45 trode 4, between cathode and grid and between
directly to an antenna the circuit I 4 may feed
anode and grid. In the case of Figure 4, if the
one or' more ampli?er or frequency multiplier
control grid is varied over a range of positive
stages before the antenna is reached. If fre
potential with respect to the cathode, we may quency multipliers are used the effective phase
dispense with the magnetic ?eld, if desired, by
50 applying sui?cient negative potential to the cold
electrode 4 to stop electrons from striking it.
'
‘ An arrangement for utilizing this variable ca
pacitive action when produced by. variable cold
electrode potential and a constant magnetic ?eld
55 is illustrated in Figure 6. A pair of electron dis?
charge devices 8, H) are provided with grid and
plate circuits I2, I4, respectively, having uni
formly distributed inductance and capacity.
These circuits are reactively associated through
60 the interelement capacity of the tubes whereby
regenerative action takes place causing the tubes
8, 10 to generate oscillations which, in turn, are
fed inductively to transmission line 16 connect
ed to a radiating antenna l8. If desired, rather
65 than ground the ?laments, the cathodes of tubes
8, I!) may be tuned, as described in the copend-.
ing applications of Nils E. Lindenblad, Serial
Number 603,310, ?led April 5, 1932, now Patent
No. 2,052,576, issued September 1, 1936 and Serial
70 Number 651,809, ?le-d January 14, 1933, now
Patent No. 2,052,888, issued September 1, 1936.
For modulation purposes the anodes or con
trol electrodes 26, 22 of electron discharge de
vices or diodes 24, 26 are connected to the out
75 put circuit 14 through radio frequency ‘by-pass
modulation is increased in proportion to the
ratio of frequency multiplication.
It should be noted that positive potential on
the anode, as shown on the ?gure, prevents an
electron cloud accumulating inside the outside
:50
electrode.
Further, in connection with Figure 6, a separate :55
solenoid may be provided for each tube and both
solenoids connected either in series or in parallel
as found desirable. Also, the cold electrodes need
not be cylindrical in a conventional manner, but
may be made cone or trumpet shaped. to give 60
variation in capacity according to any desired
law.
Rather than apply the modulating potentials
to the plates or positively maintained cold elec
trodes, modulating potentials may be applied to v65
control electrodes such as grid electrodes 43, 44
of Figure '7. Bias for these electrodes may be
maintained by suitable connections, as shown, to
potentiometer 46. Also, the plates or cold elec
trodes of the modulator tubes, in the arrange -70
ment shown in Figure ‘7, are directly connected
to the output circuit I4 rather than blocked off
therefrom by means of by-passing condensers.
The remarks concerning portions of Figure 6
with respect to tubes 8, i0 and their associated 75
2,121,737
circuits as well as the modulators, are fully ap
plicable to the arrangement shown in Figure '1
and need not be repeated here. Also, the output
energy in circuit I6 may be fed to frequency
multipliers, ampli?ers or limiters or one or more
of said devices, for example, as described in the
patents of Nils E. 'Lindenblad mentioned herein
before, before radiation by antenna 18. Such
further ampli?ers and frequency multipliers have
been diagrammatically indicated by rectangle 2|.
It is not entirely essential that a magnetic ?eld
be used for the purposes of my present invention.
That is, as illustrated in Figure 5, by applying a
negative potential to the anode or cold electrode
:15 4 and a highly positive potential on the control or
intermediate electrode. 6, electrons will rush
" 20
through the meshes of the grid or control elec
trode'only to approach the negative or breaking
?eld of the plate electrode 4. With suitable po
tentials, the electrons can be prevented from
actually reaching the plate 4 and can be caused,
as illustrated in Figure 5, to return to the space
between the cathode and grid 6 as well as to the
space immediately surrounding the control elec
25 trode 6. Variation in potential on the anode 4
or on the control electrode 6, will then cause the
effective diameter and density of the electron
cloud about the cathode and the grid to vary and
this variation in diameter will give desired varia
30 tions in capacitive reactance from the anode to
the grid and cathode. In this case the grid
should preferably be connected to the cathode
and to ground for radio frequency currents, by
~ means of by-pass condensers.
With such an arrangement, and by using such
tubes as “RCA U'X-852” it is possible to get a
usable reactance effect, due to presence of the
electrons in thetube, at carrier frequencies up
to at least 3,000 megacycles, and the phase or
40 frequency of the carrier wave may be modulated
or varied at frequencies up to at least 5 mega
cycles.
An arrangement for utilizing the effect de
scribed in connection with Figure 5 is shown in
Figure 8. Oscillations from a crystal controlled
ampli?er 5B are fed to a series of ampli?ers and
frequency multipliers 52 and thence to the input
circuit 54 of a pair of pushpull connected electron
discharge devices 56, 58 whose output in turn is
50 fed to additional frequency multipliers and am
pli?ers 60 to be radiated over antennae 62 which
is preferably a directive type. The apparatus
as so far described may correspond to any of the
systems described by Nils E. Lindenblad in the
55 copending applications already referred to. To
vary the reactance and hence the phase of energy
in input circuit 54 so as to cause the ?nal output
radiated from antennae 62 to be phase modu~
lat-ed, I provide a pair of electron discharge de
60 vices 64, 66 whose electrode emitting cathodes
68-, 15 are maintained at ground potential by lead
‘l2 and whose control electrodes or grids ‘M, 16
are maintained highly positive through lead 18
connected to source 80. For radio frequency cur
65 rents the grids are Icy-passed to the cathodes and
to ground by the condensers ‘I5, ‘H. The anodes
or plates 82, 84 are maintained somewhat nega
tive by means of potential source 86. Audio fre—
quency potentials from ampli?er 88 are applied
70 serially through the grids to transformer 90, both
grids 14, ‘i6 wobbling cophasally with the modu
3
cause the effective spacing or density of the elec
trons to vary as a result of which circuit 54 will
be Icy-passed with a capacity varying in accord
ance with the modulating potentials. These
modulating potentials are not, of course, limited i
to audio frequencies but may run into exceedingly
high present day radio frequencies in which case,
of course, ampli?er 88 would indicate‘ a source of
high frequency modulating potentials.
Figure 9 illustrates an arrangement wherein 210
magnetic or electrostatic control or both may be
had. A plurality of tubes 95], 92 are provided
with space charge grids 94, 96 suitably polarized
by sources 98, Iill]. The tubes are also provided
with control grids H32, IE4, screen grids I06, I08, 3.15
and plates or anodes III], I I2. The cathodes H4,
H6 are preferably maintained at ground poten
tial whereas the control grids I32, I043 are pref
erably negative, screen grids Il?fi, I08 are prefer
ably positive and plates H0, H2 are either posi 520
tive or negative depending upon the strength
of magnetic ?eld superimposed on the tubes. All
are polarized from potential source I I8. By clos
ing switch £20, and by manipulating key I22, a
keyed tone from source I26 will cause, by virtue ~25
of variation in screen grid potential, variable ca
pacity effects which may be transferred through
transmission line I24 to high frequency coupling
circuit E26 supplied with energy from a circuit
I28 and feeding some utilization circuit I30. As 30
an additional control of the capacity effect, switch
I32 may be closed, in which case the electron
distribution will be varied electrostatically be
cause of the variable potentials applied to the
screen grids I [56, I03 and magnetically, because of 35
the current circulating, due to closure of switch
I32, in the magnetic ?eld coils I34, I36 placed
about tubes 953, 32 in such a way that a variable
magnetic ?eld is applied to the electrons in a
direction normal to their natural paths from "40
?laments to plates. Also, switch I20 may be left
open and modulation effected solely by virtue of
the magnetic effect upon the electrons.
Further, keyed tones or other modulation of
different frequencies may be applied to the con 45
trol grids through transformer I40. By suitable
switches and circuits, similar to those‘ given in
connection with the screen grids, simultaneous
magnetic variation may be had with anode poten
tial variation and/or control grid potential varia 50
tion.
Also, if found desirable, the magnetic ?eld coils
wherever used may be electrostatically shielded
from the tubes by means of metallic cylinders in
terposed between the coils and tubes and suitably 55
grounded.
Still another means of modulating the capacity
of tubes SE], 92 may be had by varying the poten
tials upon the anodes H0, H2 as for example
through transformer I44. Obviously any com_ 60
bination and degree of modulation by all the var
ious means may be employed simultaneously
using like or different modulations on the various
means in order to obtain any desired modulation
of modulation characteristic within the limita 65
tions of the apparatus.
Having thus described my invention, what I
claim is:
1. In combination a source of high frequency
oscillations, a high frequency circuit coupled 70
the cathodes 68, ‘I0, and grids ‘I4, 16 are not
thereto, a load coupled to said circuit, an electron
discharge device having an electron emitting
cathode electrode and a relatively cold electrode
allowed to flow to the anodes 82, 86, or if so, only
to a limited extent. Modulating potentials will
to said high frequency circuit, a circuit for ap
lation frequency currents.
The electrons about
spaced therefrom, said electrodes being coupled
75
4
2,121,737
plying a magnetic ?eld to said electron discharge
device whereby electrons are prevented from flow
ing from said electron emitting cathode to said
cold electrode, and, a modulation circuit opera
tively associated with the electrons emanating
from said cathode within said device for vary
ing the distribution of electrons about said cath
ode and hence the capacity between said cathode
and said cold electrode whereby the reactance of
v10 said high frequency circuit is varied in accord
ance with modulation energy in said modulation
circuit and whereby the currents ?owing in said
load vary in accordance with said electronic dis
tribution.
2. In combination, a source of high frequency
15
necting said cold electrodes in phase opposition
to said source, of high frequency potentials, and
means for cophasally varying in accordance with
alternating potentials the instantaneous poten
tials upon said cold electrodes whereby said high
frequency currents are varied in accordance with
said alternating potentials.
5. In high frequency apparatus, a pair of mul
‘ti-electrode devices each having Within an her- .
metically sealed container an anode, a cathode 10
and a grid, a source of high frequency currents,
means for connecting said anodes in phase op
position to said high frequency current source,
means for applying cophasally to said grids, alter
nating current potentials, and magnetic means :15
oscillations, a high" frequency’ circuit’ coupled to '7 for substantially preventing the ?ow of electrons
said source whereby high frequency currents flow from said cathodes to‘ said anodes whereby said
in said circuit, a load coupled to said circuit, an
cophasal application of alternating current po
electron discharge device having an electron tentials to said grids serve to modulate said high
v20 emitting cathode electrode and a relatively cold frequency current source.
I20
electrode spaced from said emitting electrode, a
6. In combination, a pair of electron discharge
circuit connecting said electrodes to said high devices each having an anode, a cathode and a
frequency circuit, a solenoid for applying a mag~ grid, a source of high frequency currents, means
netic ?eld to said device of such strength as to for connecting said anodes in phase opposition
25 substantially prevent the flow of electrons from to said source of high frequency currents, mag .25
said cathode to said cold electrode, and, a modu
netic means for preventing the ?ow of electrons
lating circuit for applying variable modulating from said cathodes to said anodes, and means re
potentials to said cold electrode whereby the ca
sponsive to signaling waves for cophasally vary
pacity between the electrodes of said device and ing the potentials on said grids whereby said
30 hence the reactance of said circuit is varied, high frequency currents are modulated ‘in ac .30
whereby currents fed into said load are varied.
3. In high frequency apparatus, the combina
tion of a plurality of hermetically sealed devices
each having an electron emitting cathode and a
35 cold electrode spaced therefrom, magnetic means
coupled to said devices for preventing the flow
of electrons from said cathodes to said cold elec
trodes, means coupling said cold electrodes in
phase opposition to high frequency apparatus,
40 vand means for cophasally electrostatically vary
ing electronic distribution of electrons about said
cathodes.
4. In high frequency apparatus, a pair of her
>metically sealed devices each having therein an
45 electron emitting cathode and a cold electrode,
magnetic means for preventing the ?ow of elec
trons from said cathodes to said cold electrodes,
a source of high frequency currents, means con
cordance with said waves.
'7. In combination, a pair of electron discharge
devices each having an anode, a cathode and a
grid, a source of high frequency currents, means
for connecting said anodes in phase opposition 35
to said source of high frequency currents, means a
for producing a magnetic ?eld adjacent said de
vices perpendicular to the electron path between
the cathodes and anodes whereby electronslare
prevented from ?owing to said anodes from said 40
cathodes, a source of signaling potentials, and
means for varying, cophasally in accordance with
potentials from said signaling source, the poten—
tial applied to said grids whereby said high fre
quency currents are modulated in accordance 45
with said signaling potentials.
CLARENCE W. HANSELL.
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