US2045995A - Receiver especially for ultrashort waves - Google Patents

Description

Jmm 3% W36. M. PONTE RECEIVER ESPECIALLY FOR ULTRA-SHORT WAVES Filed Jan. 24, 1935 INVENTOR. MAURICE PONTE BY B ATTORNEY.

Patented June 30, 1936 UNETE STATES PATENT OFFIE RECEIVER ESPECEALLY FOR ULTRA- SHORT WAVES Maurice Ponte, Paris, France, assignor to Compagnie Generale do Telegraphic Sans Fil, a

corporation of France 2 Claims.

The present invention is useful in connection with receivers comprising the use of tubes known in the art under the name of magnetrons. It concerns various receiving systems which utilize 5 these tubes and which allow the construction of receivers intended for the reception of ultrashort waves, for which magnetrons are particularly well suited.

According to one embodiment of the invention, it has been found that a magnetron is capable of receiving, under certain field, voltage, and plate current conditions, the waves which it is able to emit, the operation underlying reception in this instance resembling the well-known operation of receivers which use retarding field type tubes of the Barkhausen-Kurz kind (based upon electron oscillations). Hence, reception in this case is a reception based upon reaction, the latter being regulated by the variables hereinafter to be enumerated, while detection is effected by and based upon the knee of the plate characteristic.

According to another embodiment of the invention, a magnetron oscillator is adapted to receive a wave, such as an ultra-short wave, by the addition of a modulation system which, in the absence of an incoming wave prevents the oscillations from attaining their normal value. Reception thus resembles that known for triode oscillators under the name of super-regenerative reception.

It is finally feasible to take advantage of the special properties of magnetron type oscillators so as to obtain from the oscillator itself, without having recourse to an exterior modulation source,

a modulation which will make it possible to insure a relatively small critical working state adapted to the reception of ultra-short waves for which magnetrons are particularly well suited.

The invention will be better understood by reference to the attached drawing, and the fuller description hereinafter by reference to the drawing. In this drawing:

Fig. 1 shows a circuit arrangement according to the principles of the first embodiment of the invention;

Fig. 2 shows the general characteristic of the plate current of the tube as a function of the plate potential, in the presence of a constant magnetic field;

Fig. 3 shows a receiver according to another embodiment of the invention; and

Fig. 4 shows a form wherein the characteristics of the magnetron creates modulation.

In Fig. 1 is illustrated a magnetron l, for instance, with two plates P, P associated with a circuit 2 with which is coupled a receiving antenna 4-4 by way of a feeder 5 and a coupling 6. It is well known that under these conditions, if in the presence of a constant magnetic field H, the plate potential is gradually raised from a sufiiciently low value, for instance, by acting upon the potentiometer 8, and the plate current being initially zero will grow rapidly to the saturation value of the tube, the slope of the characteristic Br being a function of the tube and of the associated circuits thereof. Oscillations will then arise in the circuit 2, 3.

According to the present invention, it has been found that this circuit arrangement could also be used for the reception of oscillations picked up by the antenna 4, 4, under the condition that the values of the field, of the plate potential (these two regulations being united) and of the saturation of the tube are accurately fixed. Optimum receiving conditions are those which correspond to the point R in Fig. 2. Reception could also still take place at point 1', and according to the amplitude to be received, along Rr; but the results are less satisfactory than at the point where the plate current is initiated.

The regulations required in reception for tuning of the circuit 2, 3, consist of the adjustment of the plate potential by the agency of the potentiometer 3, and that of the saturation by the heating rheostat. The field obtained by the coil 9 could likewise be regulated by the rheostat' I I, though, inside certain limits, the regulations of the plate potential and of the field are related and it sufiices to regulate one of these values.

A transformer 7, for instance, an audio frequency transformer if the transmission to be received has been modulated by an audio frequency, allows of reception by a device such as a headset l2, with the optional interposition of an amplifier !3.

In Fig. 3 is shown an embodiment of a reception arrangement according to the second embodiment of the invention. The mode of reception which precedes presents an inconvenience which makes it similar to the Barkhausen type of reception in that the regulations, for instance that of the heating of the tube, are critical, reception being practicable only for well defined values of the field, of the heating, and of the plate voltage. The second embodiment of the invention discloses a smoother or more elastic receiving principle by adapting to the tube a supplementary device such that the oscillation, in the absence of an external excitation,

are unable to assume any appreciable amplitude compared with their normal amplitilde. The reception could thus be called super-regenerative magnetron reception. According to the circuit scheme of Fig.3, it would, for? instance, be .feasible to modulate the plate: potential in the neighborhood of the point R. of Fig. 2 by means of a modulator tube I4, for instance, coupled by a transformer 55. A transtjormer 1. plays the.

same part as before mentioned.

The modulation system evidently could be of any desired kind, but according to the preferred form of the invention it has been found to be possible to utilize the characteristics of the magneltrcn oscillator to create the modulation'itselt. This preferreidform of the invention is represented in Figi l. Referring to Fig. 2, it will be conceived that if there is used in the neighborhood of the point R an anode feed device which experiences a fsufiicient fall of potential as soon as the plate current tends to grow, the starting of stable 'osciliations will be rendered impossible, the system covering the portion of the characteristic marked at, for example. According to Fig. 4, th simplest arrangement consists in connecting a condenser l8 between the feed point of the platepotential of the tube and the filament, and a resistance 56 in series with the plate current. It will be obviously advantageous to take a tube and a circuit such that the steepness "or slope of the portion Rr of Fig. 2 should be as high or great as feasible; and experience shoves that under these conditions the circuit 16 is'effectively traversed by a modulated cnrrent whose frequency may vary within very great limits. An exemplified embodiment is as follows: With a magnetron working on 3 meters, at a plate potential of 120 volts, and a saturation current of a few milliamps, thesci1cuit l6-I8-'-l is traversed by a modulated current of audible frequency, say several thousand 'cycles, with a capacity 18 of 5/10G0 of; 1 mfd and a resistance 16 of 19,000ohms. Under these conditions, the arrangement insures a strong reception of modulated Waves of 3 meters for a plate output of approximately milliaznpere. Tuning is eiiected by the circuit 2-3.

The preceding figures are merely cited by way of example. More particularly speaking, the reas indicate-d in Fig, 4 allows of the modulation ron transmitter in telegraph work using a musical note or otherwise, keying being accomplished by means of the resistance I 6.

What I claim is: a

of a magn;

I. Receiving arrangement comprising'a nagnetron tube; located in a magnetic field andghavingat leastone anode connected to a tuned circuit, energy collecting means coupled with the said tuned circuit, a load circuit coupled with the anode circuit of the tube, modulating means forthe current traversing the circuits connected to the tube, said means comprising suitable resistance in series in the anode circuit of the magnetron tube and a suitable capacity shunting said anode circuit, means for regulating the said magnetic field and the heating current and the anode potential of the tube to suchvalues that there is a detected current in the load circuit while the tube generates quenching frequency oscillations corresponding approximately to the time constant of the circuit containing saidresistance and capacity, and indicating means for the detected current. a

2. In combination, an electrical discharge detector comprising a plurality of oppositely disposed anode members, a cathode extending between said members, means for producing a magnetic field between said anode members, an input circuit connected to said anodes, means for receiving and impressing signal oscillations on said input" circuit, an output circuit connected between said input circuit and saidcathode, an

oscillation generator, and means coupled tf said i.

input circuit for impressing oscillations-from said generator upon said input circuit whereby 'a super-regenerative action'is obtained. 5

ii MAURICE PONTE.

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