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.