US1980158A - Oscillatory circuit - Google Patents

Description

Nov. 6, 1934. c w HANSELL 1,980,158

OSCILLATORY CIRCUIT Original Filed May 1, 1931 2 Sheets-Sheet 2 I l I o INVENTOR CLARENCE W. HANSELL ATTORN EY Patented Nov. 6, 1934 UNITED STATES PATENT OFFICE N. Y., assignor to Radio Corporation of America, a corporation of Delaware Original application May 1, 1931, Serial No. 534,255. Divided and this application June 6. 1932, Serial No. 615,643

17 Claims.

This case is a division of my copending application, Serial Number 534,255, filed May 1, 1931, entitled oscillatory circuits and in general relates to apparatus for generating high frequency undulatory electrical currents. In particular it relates to new and useful circuits employing electron discharge devices for generating high frequency oscillations, and resonant transmission line means for frequency controlling the frequency of oscillations generated by the devices.

In my copending application, Serial Number 400,489, filed in the United States Patent Office October 18, 1929, I have described a system employing resonant transmission line frequency control whereby, by the use of a transmission line, long, relative to the working wave length coupled to an oscillation generator, the frequency of oscillations generated by the generator is maintained constant and depends upon the line employed. 29 The frequency controlling action of the line may be attributed to the fact that the line has the effect of a sharply tuned resonant circuit whose reactance changes rapidly with change of frequency and which change of reactance is utilized to keep the frequency of an oscillator relatively constant. Since the resonant frequency of the line and the circulating current in it are determined chiefly by the length of the line, and since the line length is substantially constant, a high degree of frequency stability is obtained.

Another way of looking at this action is to consider the fact that in a resonant transmission line there will be present on the line an ingoing wave and a reflected wave. At the electron discharge quency, there will be a decided shift in phase between the ingoing and reflected waves, brought about by the waves traveling and returning along the line. That is to say, for a slight shift in frequency, there will be a shift in phase between the ingoing and reflected waves at the input end of the line directly proportional to the number of half wave lengths contained in the line. By making the line very long, the shift in phase for a small shift in frequency will be very large, as a result of which the electron discharge device oscillator will be rapidly forced back into oscillation at a desired frequency for which the phase shift between the ingoing and reflected wave is zero.

I have attempted to basically cover the foregoing system of frequency control in my copending application Serial Number 400,489. The principal object of my present invention is to provide improved circuits utilizing resonant transmission lines for frequency control.

device end of the line, with a slight shift in fre- Other objects as well as advantages of my present invention will become apparent as the description thereof, which will be given with the aid of the accompanying drawings, proceeds.

In the drawings;

Figure 1 illustrates a pushpull resonant long line frequency controlled regenerative oscillation generator wherein negative bias on the control electrodes of the devices forming the generator is imparted through a connection made at a point of substantially zero radio frequency potential on the long line frequency controlling arrangement;

Figures 1a and 1b are modifications of the arrangement illustrated in Figure 1 and in particular illustrate the use of concentric resonant transmission lines for frequency control;

Figure 2 is a similar arrangement wherein the long line couples output and input circuits of a pushpull oscillation generator, an additional half wave length circuit being provided to start and maintain oscillations at extremely high frequencies; and,

Figure 3 illustrates a system somewhat similar to Figure 2 wherein long lines of different lengths are connected to the control electrodes and anodes of a pushpull electron discharge device oscillation generator.

Figure 1 illustrates a long line frequency controlled regenerative oscillator which has been used with considerable success in actual practice. Electron discharge devices 48, 50 which may be either the air cooled or liquid cooled type have a resonant long line 6 coupled to the input electrodes 49, 51 thereof and a tunable output circuit 52 connected across their anodes 53, 55. Through the action of resistor 54 connected between the cathodes 57, 59 and the grids 51, 53 and connected to the variable slider 56 for altering the length of the line, the grids 51, 53 of the tubes 48, 50 are maintained at a suitable operating potential or negative bias with respect to the cathodes. By adjustment of neutralizing condensers 58, the amount of feed back may be controlled at will. If desired, these neutralizing condensers may be omitted and the regeneration adjusted by varying the length of the line 6 and the tuning of circuit 52 by such relative amounts as to keep the frequency fixed. As illustrated, the output circuit 52 includes a lumped inductor and a lumped variable capacitor, and the plates are maintained at a positive potential with respect to the cathodes.

Modulation may be accomplished by varying the current fiow through the modulating tubes 60 whereby the current flow through the oscillators 48, 50, is varied inasmuch as the current cuit 52 may be directly radiated, or, may be further amplified andfrequenoy multiplied by the use of additional amplifier 64 and thence radiated over a suitableantenna 66; Preferably, the antenna should be directive.

In order to check the frequency of oscillations of the system shown in Figure 1, the radio frequency'amplifier 68 may be coupled to any oscillating portion of the system so that its output feeds a detector '70 alsosupplied with energy of known frequency from, say a crystal controlled harmonic generator 72. The frequency of the beat resulting from the two sources of energy may then be indicated in a suitable indicating device 74, and, by adjustment of slider 56, so that the beat becomes of a desired value, the transmitter may be adjusted to any .suitable or desirable operating frequency. Obviously, the frequency checking and monitoring device may also be used with any of the other oscillators described.

Of course, changes may be made to the arrangement shown in Figure 1. Thus, as shown in Figures 1a and lb a parallel tuned input circuit 61 is connected across the grids 49, 51 and the resistor 54 connected from a mid-point of the tunable input circuit to the cathodes for maintaining correct bias. Moreover, this mid-point connection may be grounded by the use of a condenser 63 for radio frequency potentials. The long resonant line may then be conductively coupled to the tunable input circuit as shown in Figure la or inductively coupled to the input circuit as shown in Figure 1b.

Moreover, the long line, shown in Figures 1a and 1b may be made of concentric conductors 65, 67, variable adjustment being accomplished by the use of a disk 69 or other suitable device within the outer conductor contacting with both the outer and the inner conductor and being slidable within and along the outer conductor 65.

In the arrangementshown in Figure 2, a long resonant transmission line 6 couples the output electrodes of electron discharge devices 48, 50 to the tunable input circuit thereof. The long line 6 in this case acts both as a resonant output circuit as well as a frequency controlling medium. The input circuit 80 is preferably in the form of a coil or looped conductor substantially one-half wave length long, the wave length taken being that of a desired operating frequency. The anode potential may be supplied through radio frequency choke 82 and lead 84 upon which signal voltages are impressed through the action of a transformer 86. Output energy may be taken through blocking condensers 88 to transmission line 90 and utilized as desired.

Figure 3 illustrates an oscillator which has been found useful for producing very high radio frequencies. A long resonant line 6 is coupled to the grid electrodes of electron discharge devices 48, 50 and another long resonant line '1 pref erably of a length different from 6, is coupledto the output electrodes thereof. In this manner several standing waves on the grid and anodeleads at resonance are obtained at the desired frequency. Anode potential as well as modulating potentials are supplied through a lead 84 and fed to the anodes through the long resonant line 7. Output energy may be taken from the resonant line through transmission line 90 and radiated from a suitable antenna or radiator 92.

In order to start and maintain oscillations at the frequency higher than the lowest frequen y 1,9so,1as

for which the circuits are resonant, a circuit suchas circuit 94 is coupled to the oscillators 48, 50. This circuit has a low power factor and a minimum resonant frequency equivalent to the frequency desired. For a suitably designed circuit and proper coupling to the oscillators, the system will operate at the frequency desired. (Justomarily the circuit 94 takes theform of a U-shaped pieceof copper a half wave length long at the desired oscillation frequency and is coupled capacitively as shown to the oscillators 48, 50. The circuit 94, as shown, is closely coupled to the system through the blocking condensers 95 which act-substantially as short circuits for the high frequency currents.

Having thus described my invention, what I claim is:

1. A regenerative oscillation generating system comprising a pair of electron discharge devices each having an anode, a cathode and a control electrode, analternating current circuit connected across said anodes, means for connecting said cathodes together. a circuit comprising a pair of transversely spaced rectilinear conductors parallel to each other and having uniformly distributed inductance and capacity, each of saidconductors being more than one-half wave length long at the desired operating frequency connected to said control electrodes, and, a resistance connected between a voltage nodal point on said last mentioned rectilinear conductor circuit, and

said cathodes.

2. A regenerative oscillation generating system comprising a pair of electron discharge devices each having an anode, a cathode and a control electrode, an alternating current circuit connected across said anodes, a source of potential connected between said anodes and cathodes, a two conductor transmission line, long, relative to a desired operating wave length, operatively con nected to the control electrodes of said devices, a simple conductor connected across said transmission line to points on said line electrically remote from said control electrodes, means for subjecting saidcontrol electrodes to a suitable negative biasing potential connected between an intermediate point on said simple conductor and said cathodes, and a load coupled to said alternating current circuit.

3. A regenerative oscillation generator comprising a pair of electron discharge devices each having an anode, a cathode and a control electrode, an alternating current circuit connected across said anodes, a condenser connecting the anode of one of said devices to the control electrode of another, another condenser connecting the anode of said other device to the control electrode of one device, said condensers being adjusted to establish regeneration, between said anode circuit and said control electrodes, of a value to establish continuous oscillation generation, and frequency controlling means coupled to control electrodes of said devices, said frequency controlling means comprising a pair of rectilinear conductors having uniformly distributed inductance and capacity.

4. A regenerative system for generating high condensers, cross-connected between the anodes and control electrodes of said devices adjusted to establish feed back from said anode circuit to said control electrode circuit of a value to establish and maintain oscillations.

5. In a system for regeneratively generating high frequency oscillations, a pair of pushpull connected electron discharge devices each having an anode, a cathode, and a control electrode, a resonant circuit including a lumped inductor coupled to said anodes, and a resonant transmission line comprising a pair of rectilinear conductors having uniformly distributed inductance and capacity operatively coupled to said control electrodes, means for varying the length of said line, a resistance connected between said length varying means and said cathodes for maintaining the control electrodes to which said line is coupled at a suitable operating potential, and means connected between the anodes and cathodes for subjecting the anodes to an operating unidirectional potential.

6. A regenerative oscillation generator comprising a pair-of electron discharge devices each having an anode, a cathode and a control electrode, a circuit substantially one-half wave length long at a desired operating frequency operatively coupled to electrodes of said devices for starting and maintaining high frequency oscillations, a resonant transmission line, long relative to the wave length of oscillations generated by said de vices, coupled to electrodes of said devices for stabilizing the frequency of oscillations generated thereby, and circuits connected between the control electrodes and cathode and between the anodes and cathodes for subjecting said control electrodes to negative potentials and said anodes to positive operating potentials with respect to said cathodes.

7. A regenerative system for generating high frequency oscillations comprising a pair of electron discharge devices each having an anode, a cathode and a control electrode, a circuit having substantially uniformly distributed inductance and capacity substantially one-half wave length long at a desired operating frequency capacitively connected to the control electrodes of said devices, and, another circuit, comprising a pair of transversely spaced parallel rectilinear conductors having substantially uniformly distributed inductance and capacity several half wave lengths long at the desired operating frequency operatively connected to the control electrodes ofsaid devices, for stabilizing and frequency controlling the frequency of oscillations generated by said devices.

8. In apparatus of the character described, a pair of electron discharge devices each having an anode, a cathode and a control electrode, a circuit, having substantially uniformly distributed inductance and capacity and electrically one-half wave length long at the desired operating frequency, connected across said control electrodes, and, a pair of substantially rectilinear conductors having substantially uniformly distributed inductance and capacity and several half wave lengths at adesired operating frequency, coupling said anodes to said control electrodes.

9. A system for the regenerative generation of high frequency oscillations comprising a pair of electron discharge devices each having an anode, a cathode and a control electrode, a circuit comprising a conductor having a single loop therein and having substantially uniformly distributed inductance and capacity and substantially onehalf ,wave length long at a desired operating frequencyfcapacitively coupled in phase opposition to said control electrodesi iiotheiemircuil comprising a pair of transversely spaced subsiFaritiallr-EF y} parallel substantially rectilinear conductors having substantially uniformly distributed inductance and capacity, but many wave lengths long at a desired operating frequency connected to said control electrodes, and a third circuit comprising a pair of substantially parallel substantially rectilinear conductors having substantially uniformly distributed inductance and capacity and many wave lengths long at a desired operating frequency connected across the anodes of said electron discharge devices.

10. In a system for regeneratively generating high frequency oscillations, a pair of pushpull connected electron discharge devices each having an anode, a cathode and a control electrode, a resonant circuit coupled to said anodes, a resonant transmission line comprising a*pair of rectilinear transversely spaced substantially parallel conductors having uniformly distributed inductance and capacity connected to said control electrodes, a connection connecting the conductors together at points on said conductors electrically remote from said control electrodes, said connection having low resistance to direct currents, a biasing circuit connected between said connection and said cathodes for suitably biasing said 105 control electrodes with respect to said cathodes,

and, a circuit connected between said anodes and cathodes for subjecting said anodes to suitable operating potentials.

11. An oscillation generator comprising a pair of electron discharge devices each having an anode, a cathode and a control electrode, an alternating current circuit connected across said anodes, condensers cross-connecting the anodes and control electrodes of said devices, said condensers being adjusted to establish regeneration of a value such that continuous oscillations are generated, a rectilinear conductor connected to the control grid of one of said devices, said conductor having substantially uniformly distributed inductance and capacity, a substantially similar conductor connected to the control electrode of the other device, said conductors being arranged so as to be transversely spaced and be parallel with respect to each other, an effective direct current short circuit connection connected across said conductors, and a biasing circuit connected between said short circuiting connection and said cathodes for subjecting said control electrodes to a suitable operating potential.

12. A constant frequency regenerative oscillation generator comprising a pair of multi-electrode devices each having an anode, a cathode and a grid, meansconnecting the cathodes together, a tuned high frequency circuit connected between the grids, a high frequency circuit coupled to the anodes, means for subjecting said control grids and anodes to potentials such that oscillations are generated by said devices, and, a pair of substantially straight conductors arranged parallel to one another and arranged so as to have standing waves thereon, coupled to said tuned grid circuit for stabilizing the frequency of oscillations generated by said devices.

13. A regenerative oscillation generating sys- 1 tern comprising a pair of devices each having an anode, a cathode and a grid, means connecting the cathodes together, a resonant circuit connected between said grids, a resonant circuit connected to said anodes whereby oscillations are generated by said devices and flow in said circuits associated with said grids and anodes, and, a pair of substantially linear conductors coupled to the tuned circuit connected between said grids, said linear conductors being 4 arranged substantially parallel to each other and being spaced from.each other in such a way as to prevent radiation of energy therefrom.

14. A constant frequency oscillation generator comprising a pair of multl-electrode devices each having an anode,'a cathode and a grid, means connecting the cathodes together, a tuned high frequency circuit connected between the grids, a high frequency circuit connected to the anodes, means for subjecting said control grids and anodes to potentials such that oscillations are generated by said devices, and a pair of subed to have standing waves produced thereon, coupled to said tuned high frequency circuit connected to said grids for stabilizing the frequency of oscillations generated by said devices.

15. A constant frequency oscillation generator comprising a pair of multi-electrode devices each having an anode, a cathode and a grid, means connecting the cathodes together, a tuned high frequency circuit connected between the grids, a high frequency circuit connected to the anodes, means ---for. subjecting said control grids and anodes to potentials such that oscillations are generated by said devices, and a pair of sub-- stantially straight concentric conductors adapted to' have standing waves produced thereon, inductively coupled to said tuned high frequency circuit connected to said grids for stabilizing the frequency of oscillations generated by said devices.

16. A constant frequency regenerative oscillation generator comprising a pair of multi-electrode devices each having an anode, a cathode and a grid, means connecting the'cathodes together, a'tuned high frequency circuit connected to the grids, said tuned circuit including a lumped inductor, another tuned high frequency circuit including a lumped inductor connected to the anodes of said devices, means for subjecting said grids to .a negative potential with respect to said cathodes, means subjecting said anodes to a posi- I tive potential with respect to said cathodes, and a pair of substantially straight concentric conductors adapted to have standing waves thereon coupled to said tuned grid circuit for stabilizing the frequency of oscillations generated by said devices. stantially straight concentric conductors adaptductors adapted to have standing waves thereon conductlvely connected to said tuned grid circuit for stabilizing the frequency of oscillations generated by said devices.

CLARENCE W. HANSELL.

Images