US2379673A - Superregenerative radio receiver - Google Patents

Description

y 4 G. B. BANKS 2,379,673

SUPER-REGENERATIVE RAD IO I RECEIVER Filed Oct. 26. 1943 LZM'U III- To souect 0F INPUT s/o/vnLs NVEVTOR GEORGE 8. BAN/C5 ATTORNEY erative radio receivers.

" Patented July 3, 1945 SUPERREGENERATIVE RADIO RECEIVER George Baldwin Banks, Chelmsford, England, as-

Sig-nor to Marconis Wireless Telegraph 00.,

Ltd., London, England Application October 26, 1943, Serial No. 507,684

In Great Britain May 9,1941

4 Claims.

The present invention relates to super-regen- It also relates to velocity modulation tubes and provides a velocity modulation tube which generates two frequencies, one the operating short, or ultra-short, wave frequency and the other the quenching frequency.

Velocity modulation tubes are described in a paper which appears in the Proceedings of Radio Engineers, February 1939, at pages 106 to 116,

I and at page 113 reference is made to velocity modulation tubes operating as oscillators. It is suggested in that paper that such tubes, so operating; may be used in super-regenerative radio receivers by injecting a quenching frequency at either the collector or'focussing grid. No reference is made to the source of the quenching frequency.

According to the present invention a velocity modulation electron tube and circuit arrangement operating as an oscillator is provided with a feedback circuit extending between an electrode in said tube and the control electrode so that the tube generates, by means including said feedback circuit, and utilizesa quenching frequency oscillation in addition to the frequency generated by velocity modulation. The function of the firstmentioned electrode may be provided by the velocity modulation system as a whole, or it may consist of an anode adjacent to the cathode with a grid extending .between the said anode andcathode.

In either embodiment of the invention, both of which are illustrated in the accompanying drawing wherein Figs. 1 and 2 show diiferent embodiments of the invention, the tube includes within an envelope T, a cathode K, a control electrode 0, a velocity modulation system M and a collector electrode E. The velocity modulation system includes inner and outer cylinders z'cm and com, actually the termination of coaxial-line resonator R, the outer cylinder being provided with centrally-apertured end-.plates-epl and em and the cylinders being so coaxially disposed as to provide gaps 91 and 92 between the two ends of the inner cylinder tom and the two end-plates. The distance-between the gaps gl and g2 is such that the manner. The velocity modulation system is associated with a coaxial-line resonator R to which input signals are applied as by a coupling duce the detected signals. v

' In one embodiment of the invention, that illustrated in Fig. 1 the electrode from which the quench frequency feedback circuit extends consists of the velocity modulation system M as a whole. A retroactiv circuit RAC couples the outer conductor 00 of the coaxial line resonator R to the control electrode C so that the velocitymodulation system M as a whole acts as the anode of a three-electrode valve, the other two electrodes being the cathode K and the control electrode C. The retroactive circuit RAC comprises a parallel-tuned circuit comprising inductor LI and condenser CI. The circuit LICI has the high alternating potential side thereof connected to the outer conductor 00 0f the coaxial-line resonator R, and the other side thereof is connected to the positive terminal HT+ of a source or hightension energy (not shown). The inductor Ll is adjustably coupled to an inductor L2, and one end of inductor L2 is connected to the control electrode C through-a blocking condenser C21. The other end of inductor L2 is connected to the cathode K and to the negative terminalHT- of the said source, a'bias resistor B being connected across the control-electrode to cathode space. Since the inner cylinder icm of the modulator M is directly connected by a lead to the inner conduc tor 1C of the resonator R and the outer cylinder com is conductively connected to outer cylinder 00, the entire modulation system M will be at the high positive potential HT+. The circuit LICI is'of course tuned to the desired quench frequency. The oscillations of quench frequency interrupt the high frequency velocity modulated oscillations produced in the modulator system M. This produces the desired super-regenerative detection of the input signals.

In an alternative embodiment of the invention, V

', tension of the control electrode C the extension -time of transit of an electron is one-half cycle. Thus, the effect of the gaps is additive, in known being in the form of a cylindrical grid G surrounding the cathode. The anode 'A' consists-of a separate cylindrical member surrounding the said extension G. In this case the system comprising the cathode, grid-form extension G of the control electrode C and anode A is used as a normal three electrode valve, and ls'caused-to generate quench frequency oscillations by a simple circuit consisting of a parallel tuned circuit TC comprising inductorLl and condenser CI. The circuit TC has one end connected to the said anode A and the other end connected, through a blocking conis connected to the positive terminal HT+ of a 6 source of high-tension energy (not shown). The

cathode is connected to the negative terminal HT- of the said source. The oscillations generated in the system which simulates a threeelectrode valve are at a com- 10 ing to said control electrode a quenching oscillaparatively low frequency compared to the resonant frequency of the coaxial-line resonator R or the frequency of the incoming wave, and thereby representa modulation of the density of the election of lower frequency than the frequency tron beam, periodically quenching the oscillations enerated in the resonant circuit of the velocity modulation system. 3

It will thus be' seen that I provide means to generate oscillations of a quenching frequency which space charge modulates the electron stream.- In ig. the cathode K and control electrode C function exactly as the corresponding parts i a conventional triode oscillator. The coaxial ne resonator R produces high frequency waves by virtue of the fact that it is excited at the incoming signal frequency. v The electron stream passing through the terminating modulation elements M is velocity modulated by the excitation of the resonatorR. In Fig. 2, the cathode and control electrode of the velocity modulation system are also employed .at the quenching frequency oscillator; but here a separate anode element A is employed to complete the trlode oscillator circuit arrangement. In both places, it will I be noted, the quenching oscillator circuit arrangement is in energy transfer relation to the electron stream emanating from the cathode. which, in turn, is used both for the velocity modulation and for the quenching circuits.

What I claim is:

1. A super-regenerative radio receiver comprising a velocity modulation tube functioning as a super-regenerative detector, said tube including at least a cathode, a control electrode, a modulation element and an electron collector, and circuit means in energy transfer relation to the electron stream emanating from said, cathode for supplying to said control electrode a quenching oscillation of lower frequency than the frequency applied to said modulation element.

2. ,A super-regenerative radio receiver comprising a velocity modulation tube functioning as a super-regenerative detector, said tube including at least a cathode, a control electrode, a, modulation element and an electron collector, and circuit meansin energy transfer relation to the electron stream emanating from said cathode for supplyapplied to said modulation element, said circuit means including said cathode and said control electrode of said velocity modulation tube, and a tuned circuit. frequency, coupled to said control electrode.

3. A super-regenerative radio receiver comprising a velocity modulation tube functioning as a super-regenerative detector, said tube including at least a cathode, a control electrode, a modulation element and an electron collector, and circuit means in energy transfer relation to the electron stream emanating from said cathode for supplying to said control electrode a quenching oscillation of lower frequency than th frequency applied to said modulation element, said circuit means including a feedback circuit deriving energy for said modulation element and supplylng energy representative of said derived energy to, said control electrode, said feedback circuit including a tuned circuit resonant to the quenching frequency.

4. An ultra short wave super-regenerative receiving system comprising a velocity modulation tube, said tube including at least an electron emitter,*a control electrode a modulation element and electron collection means, an anode positioned on the side of said modulation element opposite to that at which said collection means is located, a tuned circuit coupled between said control electrode and said anode, and saidtuned circuit being resonant to the frequency of desired quenching oscillations whereby said tube functions as a super-regenerative detector.

' GEORGE BALDWIN BANKS.

resonant to said quenching

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