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Oct. 22, 1946;
2,409,897
J. A. RADO
HIGH-FREQUENCY PULSE GENERATOR
Filed Feb. 27, 1945
FIG.2
E
INVENTOR.
JOHN A. RADO
8%
“4571i
ATTORNEY
Patented Oct. '22, 1946
‘ f
UNITED I STATES
,
_
2,409,897
PATENT OFFICE
2,409,897
.
HIGH-FREQUENCY PULSE GENERATOR
John A. Rado, Little Neck, N. Y.," assignor, by
mesne assignments, to Hazeltine Research, Inc.,
Chicago, 111., a corporation of Illinois
Application February 27, 1945, Serial No. 579,955
2 Claims.
1
(Cl. 260-27)
2
.
The present invention is directed to high-fre
quency pulse generators of the type in which
pulses are generated in response to the periodic
charging and discharging of an energy-storage
device. While the invention is subject to a
It is a further object of the invention to pro
vide an improved high-frequency pulse generator
in which output pulses of the same polarity and
substantially equal amplitudes are obtained in
response to both the charging and discharging
of an energy-storage device.
variety of applications, it is especially suited to
generator arrangements in which the energy
In accordance with the invention, a high-fre
quency pulse generator comprises means for sup
storage device is charged and discharged through
plying a unidirectional potential to the generator,
gasdilled electron-discharge devices and will be
particularly described in that connection.
10 having one terminal connected to a common ter
minal of the generator maintained at a, ?xed
As utilized throughout the present description
reference potential and having a second termi
and in the appended claims, the expression “high
nal by-passed for alternating currents to the
frequency pulse generator” is intended to des
common terminal. The arrangement has an
ignate a generator for producing output pulses
which may occur at high repetition frequencies. 15 energy-storage device, including a transmission
line section having an input terminal and hav
A high-frequency pulse generator of the type
ing- shunt-connected condensers half of which
undervconsideration is disclosed in copending ap
are connected between the second terminal of the
plication, Serial No. 579,954, filed February 2'7,
potential-supplying means and the input termi
1945, in the name of John A. Rado and assigned
to the same assignee as the present invention.
In that arrangement, a transmission-line section
is utilized as an energy-storage device, being
charged from a potential source through a vac
uum tube and thereafter being discharged rap
idly through a gas-?lled tube. A pulse trans
former coupled into the discharge circuit of the
line section ‘supplies an output pulse of a given
polarity to a load circuit upon each discharging
nal while the remaining half are connected be
tween the common and input terminals. The
generator has means for eiiectively connecting
the input terminal to the second terminal of the
potential-supplying means to provide a charging
25 circuit for establishing a predetermined charge
on the energy-storage device in a time interval
which is short with reference to the minimum
period of the generated pulses.
Additionally,
means are provided for effectively connecting the
desirable operating characteristics. For example, 30 input terminal to the common terminal to pro
vide a discharge circuit for the energy-storage
the generated pulses have a substantially rec
device which is electrically equivalent to its
tangular wave form and a duration approximately
charging circuit. The desired output pulses are
equal to 2\/LC, where L and C, respectively, des
obtained through means coupled to the charg
ignate the total inductance and total capacitance
of the line.
Such an arrangement has very
ing and discharging circuits for deriving an out
of the transmission line. Also, pulses of high
put pulse of -a given polarity and amplitude in
peak power may be generated while thearrange
response to the charging of the energy-storage
ment operates at moderate supply voltages, thus
device and for deriving an output pulse of the
obviating the necessity for an elaborate high
same polarity and approximately the same am
voltage power supply and reducing the equipment
plitude in response to the discharging of the en
cost and shock hazards.
40
ergy-storage device. Finally, the generator has
arrangements of the type described in the
means for controlling the charging and discharg
above-identi?ed copending application, produce
ing circuits alternately to charge and discharge
desired output pulses only in response to the dis
the energy-storage device so as to generate out
charging of the energy-storage device. By con
structing the pulse generator to produce output 45 put pulses of the above-mentioned given polarity
pulses of a given polarity in response :to the
charging as well as the discharging of its energy
and amplitude and occurring in a predetermined
storage device, very high pulse-repetition fre
-' For a better understanding of the present in
time
sequence.
I
-
vention, together with other and further objects
.
'
_
,
‘It is an object of the present invention, there 50 thereof, reference is had to the following descrip
quencies may be obtained“ '
fore; to provide an improved high-frequency pulse
generator in which output pulsesof the‘same
tion taken in connection with the accompanying
polarity are derived in response to the charging
as well? as the discharging of an energy-storage
appended claims. ,
device.
'
,
drawing, and its scope will be pointed out in the
In the drawing, Fig. 1 is a'schematic circuit
55 diagram of a high-frequency pulse generator in
2,409, 897
3
4
accordance with the invention; Fig. 2 is a series
sented comprises an energy-storage device in the
so poled that an output pulse of a given polarity
is induced in winding 2‘! in response to the charg
ing of the line section, while an output pulse of
the same polarity is induced in this winding in re
sponse to the discharging of the line section, A
suitable utilizing circuit may be coupled to the
terminals associated with winding 21 for utilizing
the output pulses supplied by the generator.
form of an arti?cial or simulated transmission
Preferably, the load circuit of transformer i1, 25,
of graphs utilized in explaining the operation of
the Fig. 1 arrangement; while Fig. 3 is a sche
matic representation of a portion of the Fig. 1
arrangement in modi?ed form.
Referring now more particularly to Fig. 1 of
the drawing, the pulse generator there repre
line section I0 having an input terminal H. The 10 and 21 is so arranged that, when either charging
line is formed of lumped circuit elements, includ
tube IE or discharging tube 25 is rendered con
ing series-connected inductors l2, l2 and inter
ductive, the impedance coupled to the input ter
mediate shunt condensers I3, l3 arranged to
minal of line section I0 corresponds to its char
de?ne ?lter sections. A sufficient number of such
acteristic impedance. This proportioning of the
?lter sections are provided so that the line sec
tion l0 in charging and discharging may deliver
energy to a load circuit substantially continuously
during a desired pulse interval. The line is un
terminated at one end and may be considered
r load circuit of the transformer assures maximum
power transfer from the generator.
The generator additionally includes means for
controlling the described charging and discharg
ing circuits alternately to charge and discharge
to be open-circuited.
20 the line section l0‘ so as to generate output pulses
The generator also comprises a charging circuit
of a given polarity and occurring in a predeter
for establishing a predetermined charge on line
mined time sequence. Where, as in the embodi
section It! in a time interval which is short with
ment under consideration, the charging and dis
reference to the minimum period of the generated
charging circuits individually include electron
pulses. As here used, the expression “period of 25 discharge tubes normally maintained in a non
the generated pulses” is intended to de?ne the
conductive condition, the instant means is uti
time interval between corresponding portions of
lized alternately to render the tubes conductive.
succeeding ones of the generated pulses. This
The time sequence in which the tubes are ren
charging circuit is provided by a connection 14 to
dered conductive determines the time sequence
ground from line section I0 and a resistor IS, a
or repetition frequency of the generated pulses.
?rst gas-?lled electron-discharge device or tube
The control means, as illustrated, is provided by
l6 of the tetrode type, and a ?rst winding section
an input terminal 40 to which may be applied a
I‘! of a pulse transformer which serially connect
control signal for application to the control elec
the input terminal I I to a source of unidirectional
trodes of tubes l6 and 25. Terminal 40 is coupled
potential, indicated +3 The potential source is 35 by means of a condenser 4| and leak resistor 42
icy-passed to ground for alternating currents by
to the input circuit of a cathode follower, includ
way of a condenser l8 which is large with refer
ing a triode Vacuum tube 43. The cathode imped
ence to the line condensers I3.
ance of tube 43 consists of a self-biasing resistor
The line-charging tube I6 is normally main
44 in series with a resistor 45. An ampli?er, in
cluding a triode 46, is cathode-coupled to cathode
tained in a nonconductive condition. To this end,
its control electrode is held at a ?xed negative
follower 43 and includes in its output circuit the
potential with reference to ground by means of a
primary winding of pulse transformer 2|. The
potential source —Ec and resistors l9 and 20 con
control electrode of charging tube !6 is coupled
nected thereacross in series, while the cathode
to the control circuit by way of this pulse trans
potential with respect to ground is determined 45 former. The control electrode of discharging
primarily by the charge condition of line section
tube 25, however, is coupled through a condenser
10. The control electrode of tube I6 is connected
41 to the output circuit of ampli?er 46. lA volt
to potential source -—Ec through the secondary
age divider 48 is utilized in establishing a bias po
winding of an additional pulse transformer 2|.
tential on the control electrode of tube 46 and
The screen electrode of this tube is maintained at 50 condenser 49 is employed as a blocking condenser.
the potential of its cathode and the control elec
The described control circuit, in conjunction with
trode is coupled to its cathode by way of a con
the potential source -—Ec associated with the con
denser 22.
trol electrodes of tubes l6 and 25, serves to control
There is also provided in the pulse generator 8.
the charging and discharging circuits in a man
discharging circuit for discharging line section II)
ner presently to be described.
in a time interval which is short with reference to
In considering the operation of the pulse gen
the minimum period of the generated pulses. The
erator, it will be assumed initially that line sec
discharging circuit includes a second gas-?lled
tion I!) is completely discharged. For this condi~
electron-discharge tube 25 and a second winding
tion, the cathode of charging tube I6 is at sub
section 26 of the ?rst-mentioned pulse trans 60 stantially ground potential and the negative po
former which serially connect input terminal H
tential applied to its control electrode from source
to conductor l4. Discharge tube 25 is similar to
—'Ec causes this tube to be nonconductive. Like
the charging tube l6 and is likewise normally
wise, the discharging tube 25 is nonconductive due
maintained in a nonconductive condition. For
to the bias on its control electrode which is select
this purpose, the control electrode of tube 25 is 65 ed through adjustment of variable resistor 30 to be
connected to an adjustable tap of a variable re
much larger than the negative potential on the
sistor 30 included in a biasing circuit consisting of
control electrode of tube l6. It will be assumed,
potential source -—Ec, variable resistor 30, and re
further, that a control signal of the type repre
sistors 3|, 32, and 33.
sented by curve A of Fig. 2 is applied to control
A third winding section 21 of the ?rst-men 70 terminal 40 from a signal source, not shown in
tioned pulse transformer provides means in the
the drawing. The control pulses are translated
generator, coupled to the described charging and
through cathode follower 43 and ampli?er 46 and
are applied with positive polarity to the control
in response to both the charging and discharging
electrodes of charging tube l6 and discharging
of line section I0. Winding sections I1 and 26 are 75 tube 25. The ?rst pulse of the applied control
discharging circuits, for deriving output pulses
‘2,409,897
6
signal initiates an electron discharge in tube [6
but is unable to overcome the bias potential on
tube 25 which remains nonconductive.
. With tube I5 conductive, the charging circuit
of line section I0 is energized. Transformer
windings I1 and 21 effectively apply an imped
the same polarity and duration as the preceding
pulse P6,, resulting from the line charging proc
ess. The step portion S: of curve D designates
the potential drop in the anode-cathode circuit
of tube 25 during the pulse interval ta-tr in
which this tube is conductive.
,
ance'to the input terminals of line section I 0
which is equal to its characteristic impedance and
The remaining control signals of curve A re
l6, and the anode of tube 25, respectively, are
represented by those portions of curves B, C, and
impedance-path would be established across po
tential source +B. This undesired result is ob
peat the described cycle of operation in which
the line section is ?rst charged to derive an
the potential at the input terminals of the line
immediately rises to approximately half the value 10 output pulse and then discharged to derive the
succeeding output pulse. Curve E represents the
of source +B. After a predetermined pulse, in
time sequence of the generated pulses which will
terval, described hereinafter, the line becomes
be seen to correspond with that of the applied
fully charged and the potential level of its input
control pulses. In selecting the control signal, it
terminals is then approximately equal to that of
source +B. Consequently, the cathode potential 15 is necessary that the time separation between
succeeding pulses thereof be more than the de
of charging tube l6 and the anode potential of
ionization interval of charging tube l6 and dis
discharging tube 25 are raised a corresponding
charging tube 25. In other words, while these
amount, biasing tube 16 once again to its none
tubes are rendered conductive in alternation,
conductive state and reducing the bias level of
tube 25 to condition the latter to respond to the 20 neither is rendered conductive until the deioniza
tion interval of the other has passed. It will be
next pulse of the control signal.
clear that if tube 25, for example, were triggered
The described potential variations at the input
during the deionization interval of tube IS, a low
terminals of line section Hi, the cathode of tube
viated by spacing the pulses of the control signal
in the manner mentioned above.
~
I
lines t1 and t2, where h is the instant at which
The generator of Fig. l is effective to produce
the ?rst pulse of the control signal is applied and
output pulses of high repetition frequencies, lim
232 is the instant when the line has become fully
charged. The charging current which flows in 30 ited only by the deionization intervals of tubes
the pulse interval t1——-t2 induces an output pulse
I6 and 25. The maximum repetition frequency
of a given polarity in transformer winding 21 for
is obtained when these tubes are so controlled
application to a utilizing circuit coupled thereto.
that each is rendered conductive immediately
The output pulse thus obtained in response to
following the deionization interval of the other.
the charging of line section I0 is represented by 35 In addition to providing pulses of high repetition
frequencies, the generator has the advantage of
pulse Pi».1 in curve E of Fig. 2. Its duration is
high e?iciency. This follows from the fact that
approximately equal to ZVLC, where L and C,
the energy available in both the charging and
~respectively, are the total inductance and total
discharging process is utilized in deriving output
capacitance of the line section. During the pulse
interval t1—-}tz,'charging tube I6 is conductive and 4.0 pulses.
The wave forms of the curves of Fig. 2 have
the step portion S1 of curve C shows its cathode
been idealized to simplify the description. As a
potentialto be equal to the source +B minus the
practical matter, the pulses obtained in the
potential drop of its anode-cathode circuit.
charging process have a smaller amplitude than
When the next succeeding pulse of the control
signal is translated through tubes 43 and 4.6 to 45 those resulting from the discharging process.
This is due to the dissimilarity of the charging
the control electrodes of tubes I6 and 25, the
and discharging circuits. In this connection, it
positive potential of the cathode of tube 16 causes
will be noted that the discharging circuit in
this tube to remain in its nonconductive. state
but, in view of the reduced bias on tube 25, the - ' veludes only the line section I 0, winding 26 and
latter is rendered conductive. With tube 25 con 50 discharging tube 25, while the impedance ele
ments involved in the charging process are the
ductive, the discharging circuit of line section In
line section l0, winding I1, charging tube l6, and
is energized and the potential at the input ten
by-pass condenser l8.‘ Where the charging and
minals of the line is immediatelyvreduced from
discharging circuits are electrically equivalent
its value of source +3 to approximately half that
value. After a given pulse interval, determined 55 to one another, the output pulses have the same
amplitude as well as the same polarity. ’
by the inductance and capacitance of the line,
D of Fig. 2 which are included within ordinate
the line becomes completely discharged, retum
' Fig. 3 represents a modification of the charg
ing and discharging circuits of the Fig. I arrange
ing its input terminals to ground or zero poten
ment with which output pulses of equal ampli
tial. The cathode of charging tube l6 and the
anode of discharging tube 25 are likewise brought 60 tudes are obtained. The components of Fig. 3
which correspond to those of Fig. 1 are identi?ed
to ground potential, conditioning tube I6 to re
by the same reference characters. As in the Fig.
spond to the next pulse of the control signal and
1 arrangement, one terminal 60 to which source
biasing tube 25 to its initial, nonconductive state.
+B is applied is connected to a common terminal
The described potential changes which accom
pany the discharge of line section H] are repre 65 that is maintained at a ?xed reference potential,
speci?cally ground, while the alternate terminal
sented by those portions of curves B, C‘, and D
6| for receiving source +B is by-passed to ground
included between the ordinate lines is and 114,
by way of condenser I8. Line section Hi again
where is is the instant at which the second pulse
includes shunt-connected condensers, half of
of the control signal occurs and t4 is the instant
when the line is completely discharged. Current 70 which-designated by numeral 50, 50, arecon
nected by way of conductor 52 between input ter
flow through the transformer winding 26 in the
minal II and the high potential terminal 6| of
discharging of the line section induces in wind
ing 21 a second output pulse. This pulse ob
source +B, while the other half, indicated 5|, 5|,
"tained in response to the discharging of the line
are connected between input terminal II and
section is represented at Pa1 of curve E and has 75 ground through connection ll. Otherwise, the
l
2,409,897
8
circuit arrangement is identical with the corre
sponding portion of Fig. 1 and may be controlled
by the same type of control circuit to generate
output pulses. The control circuit, however, has
been omitted to simplify the drawing.
In considering the operation of the Fig. 3 em
bodiment, assume that tubes i6 and 25 are in
having a second terminal by-passed for‘alternat
ing currents to said common terminal, an energy
storage device including a transmissiondine sec
tion having an input terminal and having shunt
connected condensers half of which are con
nected between said second terminal of said po
tential supplying means and said input terminal
while the remaining half thereof are connected
between said common terminal and said input
their normal, nonconductive states. By-pass con
denser IB. is charged from source +3 and the line
condensers 50, 5!] and 5|, 5| form a capacitive 10 terminal, means for eiiectively connecting said
type voltage divider coupled across by-pass con
input terminal to said second terminal -of said
denser IB. The line condensers then acquire
potential supplying means to provide a charging
identical charges, individually equal to half the
circuit for establishing‘ a predetermined charge
value of the source +B. If charging tube I6
on said energy-storage device in a time interval
is triggered, a short circuit is effectively estab 15 which is short with reference to the minimum
lished across line condensers 5|], 50 so that the
period of the generated pulses, means for effec
alternate condensers 5|, 5| receive a'charge equal
tively connecting said input terminal to said com
to source +B and condensers 5|), 5|! are dis—
mon terminal to provide a discharging circuit for
charged. The current flow through the network
said energy-storage device which is electrically
in this process provides one output pulse of a 20 equivalent to said charging circuit, means cou
given polarity and amplitude. If , now, discharg~
pled to said charging and discharging circuits
ing tube 25 is rendered conductive, a short cir
for deriving an output pulse of a given polarity
cult is effectively established across condensers
and amplitude in response to the charging of
5|, 5| which discharge and supply a second
said energy-storage device and for deriving an
output pulse while condensers 50, 59 become fully 25 output pulse of the same polarity and approxi
charged. The circuit is now conditioned to gen
mately the same amplitude in response to the dis
erate a third pulse in response to the trigger
charging of said energy-storage device, and
ing of tube I6 and the charging of condensers
means for controlling said charging and dis
5|, 5|. Thus, in the Fig. 3 arrangement, con
charging circuits alternately to charge and dis
densers 5|, 5! constitute the energy-storage de 30 charge said energy-storage device so as to gen
vice which is alternately charged and discharged
erate output pulses of said given polarity and
to generate output pulses. The pulses obtained
amplitude and occurring in a predetermined time
thereby are of the same polarity and equal am—
sequence.
plitude since in each operation half of the line
2. A high-frequency pulse generator compris
condensers are charged to the potential level of 35 ing, means for supplying a unidirectional poten
source +B while the other half become dis
tial to said generator having one terminal
charged, and since identical impedances are in
grounded and having a second terminal by
volved in each case.
passed for alternating currents to ground, an
In each of the described embodiments of the
energy-storage device including a transmission
invention, gas-?lled tubes are employed in the 40 line section having an input terminal and having
charging and discharging circuits in order that
shunt-connected condensers half of which are
their high current-carrying capacity may be ex
connected between said second terminal of said
ploited to generate output pulses of high power.
potential supplying means and said input termi
If desired, vacuum tubes may be utilized in their
nal while the remaining half thereof are con
stead in which case no deionization phenomenon . nected between ground and said input terminal,
is involved and increased repetition frequencies
means for effectively connecting said input ter
limited only by tube dissipation capabilities are
minal to said second terminal of said potential
possible.
supplying means to provide a charging circuit
Pulse generators constructed in accordance
for establishing a predetermined charge on said
with the teachings of this invention are subject
energy-storage device in a time interval which
to a variety of applications. In the communica
is short with reference to the minimum period
tion ?eld, for example, they may be used to
of the generated pulses, means for effectively
pulse-modulate a transmitted carrier-wave sig
connecting said input terminal to ground to pro
nal. In industrial ?elds they may be included in
vide a discharging circuit for said energy-storage
welding systems and the like.
device which is electrically equivalent to said
While there have been described what are at
charging circuit, means coupled to said charging
present considered to be the preferred embodi
and discharging circuits for deriving an output
ments of this invention, it will be obvious to
pulse of a given polarity and amplitude in re
those skilled in the art that various changes and
sponse to the charging of said energy-storage
modi?cations may be made therein without de 60
device and for deriving an output pulse of the
parting from the invention, and it is, therefore,
same'polarity
and approximately the same ampli
aimed in the appended claims to cover all such
tude in response to the discharging of said
changes and modi?cations as fall within the true
energy-storage device, and means for controlling
spirit and scope of the invention.
said charging and discharging circuits alternately
What is claimed is:
65 to charge and discharge said energy-storage de
1. A high~irequency pulse generator compris
vice so as to generate output pulses of said given
ing, means for supplying a unidirectional poten
polarity and amplitude and occurring in a prede~
tial to said generator having one terminal con
termined time sequence.
nected to a common terminal of said generator
maintained at a ?xed reference potential and 70
JOHN A. RADO.
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