US2565708A - Electronic valve for operating on very short waves - Google Patents

Description

1951 R. WARNECKE ET AL 2,565,708 7 ELECTRONIC VALVE FOR OPERATING ON VERY SHORT WAVES 2 Sheets-Sheet 1 Filed May- 21, 1947 INVENTOR ROBERT WARNECKE JEAN BERNIER AGENTS B HH HMMH n Am O m 1951 R. WARNECKE ETAL 2,565,708

ELECTRONIC VALVE FOR OPERATING ON VERY SHORT WAVES 2 She ets-Sheet 2 Filed May 21, 1947.

INVENTOR ROBERT WARNECKE JEAN BERNIER AGENTS Patented Aug. 28, 1951 ELECTRONIC VALVE FOR OPERATING ON VERY SHORT WAVES Robert Warnecke and Jean Bernier, Paris, France,

assignors to Compagnie Generale de Telegraphic Sans Fil, a corporation of France Application May 21, 1947, Serial No. 749,468 In France September 19, 1942 Section 1, Public Law 690, August 8, 1946 Patent expires September 19, 1962 4 Claims.

This invention is relating to electronic valves operating on very short waves.

It is now well known that certain of the principal phenomena which in the case of ultrashort waves oppose an eflioient functioning of the ordinary valves, are due to the fact that in these valves the high frequency control signal contributes in communicating to the electrons their kinetic energy.

In the valves known as velocity modulation, the fundamental difii'culties resulting from this process of control, reduction of the input impedance in particular, have been remedied by employing a high frequency signal only to cause the velocity of the electrons in movement to be varied periodically by a fraction generally slight, of its value; the modulation in intensity of the current conveyed by the beam being carried out later on, in a space called space of collection, by a grouping of the electrons due simply to the effect of the differences of their individual velocities. Thus, the high frequency energy necessary for the control is very slight, whilst the kinetic energy of the electrons is taken primarily from the source of continuouspotential serving to accelerate the electrons.

In spite of its great advantage with respect to the ordinary process of control used in triodes or other valves of the same nature, the foregoing method is not completely satisfactory since the most efficient electronic grouping which can be obtained by known means in valves known as velocity modulation valves, leads-under the best conditions of construction and regulation-to a theoretical output value systematically limited and well below 100%; in the case of a longitudinal velocity modulation transformed into a density modulation by drift of the electrons in a space free from a held, this extreme theoretical value is about 58%, it being understood that the efiiciency constitutes the ratio of the high frequency energy given up by the beam to the collector to the energy spent in the source of continuous current potential serving to accelerate the electrons.

The present invention has for its object to improve considerably the efliciency of all valves which are based, in the main, on a periodically variable transit time of the electrons resulting from the action on the beam of an adequate system of control, such as velocity modulation valves with control by longitudinal action or by transverse action of a high frequency field.

This invention consists in a particular arrangement and novel design-oi the system of control for amplifier valves; and at the same time of the system of control and of the collector system for auto-oscillator valves.

The characteristic element common to all valves of the type forming the object of the invention is a particular arrangement of the system of control. The improyed design on which this arrangement is based is the simultaneous action of several high frequency fields of suitable form which will be determined hereafter in such manner that the electronic current wave result ing therefrom, lends itself better to a considerable exchange of energy with the high frequency held, or the high frequency fields of the collector.

It can be proved that the fact that the transit time is sinusoidal but of the form where is the output phase of the electrons from the control system, and 7c is a whole number, produces under the best adjustment conditions a gain in efficiency of 16%, whilst the form only gives a supplementary gain of 1.4%. It can be shown that the gain made by adding harmonics of higher and higher order to the transit time is less and less although the maximum efliciency thus does tend towards when approaching the ideal form Actually, this form expresses the condition at which all the electrons issuing from, the control system in the course of a period pass at the same time into the collector and this when its electric field is a retarding one and a maximum.

It will be easily understood that in order to obtain such optimum forms of the duration of travel of the electrons between the control system and the collector'system, the disturbance of control must be 'a superposing of harmonic disturbance. If it were possible to produce in decimetric or centimetric waves potentials of a form freely capable of adjustment by means of external generators, it would consequently be possible to improve the efiic'iency' of the transit time generators which the invention has in view, at least when they are used as amplifiers, retroactive or otherwise, up to a value of approximately 100% and this without the use of any particular system of electrodes.

according to one characteristic of the invention of making up of this ideal external generator by making us of energy which can be found, in particular in the interior of the valve, according to another characteristic of the invention.

There will now be described the particular arrangement of the electrodes of the system of control of the valves forming the object of the invention. The object of this arrangement is to permit an optimum disturbance or a disturbance close to the optimum disturbance or perturbation to be applied to the beam resulting from the preceding generalities by the simultaneous action of several harmonic high frequency fields.

The embodiment of my invention as described herein is illustrated in the accompanying drawing in which:

Figures 1a and 1b show, diagrammatically, and respectively the electrode arrangement for longitudinal and transverse action of the high frequency field on the beam;

Figure 2 shows diagrammatically a velocity modulated beam tube with longitudinal control and using a drift space;

Figure 2a is a fragmentary view showing a modification of Figure 2 wherein the adjacent cavity resonators are separated;

Figure 3 shows diagrammatically an electrode arrangement for a velocity modulated beam tube with transverse control;

Figure 4 shows diagrammatically an electrode arrangement for the collector of the beam tube operating in accordance with a characteristic of the present invention;

Figure 5 is a diagrammatic showing of a velocity modulated beam tube having control and collector systems in accordance with my invention and adapted to operate as a self-oscillator;

Figure 6 is a diagrammatic showing of a velocity modulated beam tube with longitudinal control and employing a deflector field; and

Figure 7 shows diagrammatically a velocity modulation valve with retarding field.

It is necessary to distinguish as to whether the velocity modulation valve is controlled by longitudinal action or by transverse action of the high frequency field on the beam.

(a) For valves controlled by longitudinal action, the system of electrodes is diagrammatically illustrated in Figure 1a. It is essentially composed of a series of metallic gratings A, B1, B2, B3 B1 of single or multiple meshes located on the path of the electronic beam issuing from the cathode K and disposed perpendicularly to the beam. For the convenience of the explanation but without many restrictions as to the scope of the present invention, it will be assumed that these gratings are flat, parallel, completely equipotential and ideally permeable to the electrons. According to the principle of the present invention, there are applied between these gratings sinusoidal horizontal potentials u1=U1 sin wt, u2=U2 sin Zwt, un=Un sin not having preferably small amplitudes U1, U2 Un with respect to the continuous current potential U0 corresponding to the mean velocity '00 of the electrons. Without being restrictive, it will be the same between all the gratings, that is to say, that all the gratings will be raised to the continuous potential Uo.

(b) For valves controlled by transverse action, the system of electrodes is illustrated diagrammatically in Figure 11). It is composed of several pairs of electrodes B1, B2, B3 B1, capable furthermore of being reduced to wires each pair being arranged axially of the beam. It is known that with this class of control it is the longitudinal component of the high frequency field occasioned by the deformation of the field lines at the edges of the electrodes which causes the modulation of longitudinal velocity necessary for the creation of a wave of utilisable current and that the frequency of this phenomenon is in general double the frequency of the high frequency field. Consequently, if m is the pulsation of the field of the collector there will be obtained between the couples of deflection electrodes B1, B2 Bn transverse high frequency fields of pulsation w/2, 2w/2, 3w2 which can be considered as created by potentials u1=U1 sin ll/2t, 1L2=U2 sin wt of slight amplitudes with respect to U0.

Itis quite understood that the diagrams comprising Figures la and 112 do not restrict the scope of the present invention. Thus, the number of the electrodes and the order in which the high frequency potentials are applied may be different; the electrodes may be raised to different continuous current potentials, they may be separated by spaces free from high frequency fields as shown in Figure 2a and indicated theoretically in Figure 1a, several couples of electrodes may correspond to the same pulsation of the high frequency field; the electrodes of Figure 12) need not be parallel nor at the same level.

It will be evident to any person skilled in the art that by suitably regulating the amplitudes of the potentials U1, U2, U3- there may be found at the outlet of the control system a disturbance of velocity necessary for the transit time of the electrons which approaches the ideal law and consequently obtain a higher efiiciency than that which is found with known valves employing a single oscillating electric field for the control. If, in particular, for valves with longitudinal control there is employed a system of three electrodes A, B1, B2 fed by two sinusoidal potentials U1 sin of and U2 sin 20:15, it will be possible to obtain for the ideal valve conceived according to the present invention a theoretical efiiciency of approximately 73% and this according to What has been stated above, with a negligible high frequency control power.

One method of carrying the invention into effect will now be described with reference to Figure 2, wherein a velocity modulation valve 'withlongitudinal control employing a system of electrodes in which the transformation of the velocity modulation into density modulation is obtained by drift of the beam in a space free from electric field.

Like most of the examples hereinafter described, the valve has oscillating circuits comprising resonant spaces of revolution about the axis of the electron beam, having a profile of retracted form and known as rhumbatron, but it is to be clearly understood that this particular type of oscillating circuit is only given by way of example and can be applied to transit time valves for very short waves, the associated oscillating circuits of which comprise other systems such as sections of transmission lines or wave guides.

In Figure 2, an emissive cathode K is shown as heated by a filament F; in front of the cathode K are placed three gratings or grids A, B1 and B2. A and B1 are incorporated in the walls of a rhumbatron R1; B1 and B2 in the walls of a rhumbatron R2. The rhumbatrons R1 and R2 are illustrated with a common wall but this particular arrangement is not obligatory and in no way restrictive, as the rhumbatrons R1 and R2 may be separated by a space in which, for example, there is no field. A Faraday cage 12 formed for example by a metallic tube electrically eonnects the gratings B2 and M. M and N and MN and NN are the electrodes between which the electric field acts which is developedin the energy collector formed by a rhumbatron R3 and others that may be used. With the arrangement illustrated in Figure 2, A, B1, B M and N are raised to a constant potential U0. P is an electrode which collects the electrons after their passage in the collector due to a positive polarisation Up which is regulated to a value just sufficient to collect them all. The rhumbatrons R1 and R2 are designed and adjusted in such manner as to have reciprocally self-oscillation pulsations equal to 2w and w, .0: being the vibration pulsation of the rhumbatron R3 If R1 and R2 are excited with alternating potentials of pulsations 2c and w and of suitable phase so that the fields acting longitudinally of the beam have slight amplitudes but in the ratio of approximately 1 to 2 according to the elementary theory developed above, and if, the distance 52M is judiciously chosen to correspond to the potentials according to the said theory, then the duration of transit of the electrons between B2 and M is given by the equation hereinabove stated and the efiiciency of such a valve will be approximately 73%. This result assumes that the effects of the space charge and of the transit time of the electrons in the collector are negligible, but it will be seen that the efficiency is much higher than that of usual velocity modulation valves where the system of control only comprises a field of pulsation w' and the maximum emciency of which upon the same hypotheses, is 58%.

As has already been described, the valve illustrated in Figure 2 supplying energy on the pulsation is requires two control potentials, one at the pulsation w and the other as the pulsation 2w. As has been explained above, these two potentials may be chosen very small by providing a suitable construction and the corresponding. high frequency powers may then be very small compared with that which appears in the collector. A fraction of the latter appearing negligible at first, may thus be taken from the collector R3 and delivered in correct phase into the rhumbatron R 2 to furnish the excitation at the pulsation w. This may be produced by means of the coupling line I shown dotted, connecting the loops b2 and b3 located respectively in the rhumbatrons R2 and R3 (where they surround a magnetic flux). The valve obtairied'rriay then be considered as a retroactive amplifier which, excited by an independent high frequency source of pulsation 20: supplies energy at the pulsation w. This useful energy may be, as is well known, transmitted to the utilisation load by a line 14 connected to a loop b4 which is located in the collector.

There will now be briefly described by way of amiaa second example, a velocity modulation valve with transverse control, provided with a device according to one of the principal characteristics of the invention.

In this example (Figure 3) the oscillating circuits (L131) (L2B2) and C are formed of sections of a transmission line, K is the cathode, P the electrode collecting the electrons (at a potential Up 0, with respect to K just sufiicient to collect all the electrons), D is a diaphragm serving at the same time as a focalising lens, B13 2 are the two pairs of electrodes of the control system, G1G2 the grids limiting the high frequency field of the collector C; D, 131, B2, G1, are at the same continuous current potential U0.

L1 is the quarter wave element of the transmission line which, connected to the pair of electrodes B1 forms an oscillating circuit of pulsation 02/2.

L2 is the quarter wave element of the transmission line which, connected to the pair of elec trodes B2, forms an oscillating circuit of pulsatiOl'l w.

L'3L"3 are elements of the transmission line which formwith G1G2 an oscillating system of pulsation w.

7 b1 is the coupling loop of L1 with the source S of pulsation (0/2, and is connected to the latter by the line Z1.

ha is the coupling loop of L's with the utilisation circuit 13 and b2 is the coupling loop of L2 with the source of pulsation w.

L2 can be excited by means of a small part of the energy of the collector connecting 192 by a line Z to a loop bs placed in the vicinity of L3. The valve can then be considered as a regenerative amplifier which, excited by an independent high frequency source of pulsation w/2, delivers energy at the pulsation w.

Regulation takes place by acting on the coupling loops b1, b2, b3, 17's, as also on Z1 and Z.

In order to convert, according to the principle of the present invention, the valve with longitudinal control of Figure 2, into an autonomous auto-oscillator, there may be employed an energ'i collector forming the object of the second principle characteristic of the present invention.

This collector is arranged in such mannerthat it causes several high frequency electric fields (more or less limited) oscillating with pulsations.

w, 2w, 3w to act on the beam which passes through it.

It is composed essentially (Figure 4) of a set of metallic gratings M, N1, N2 N17, which are similar to the gratings A, B1, B2 B2 serving as elements to the system of control of Figure 1a and are arranged in the same way as those with respect to the beam. M and N1 are incorporated or connected in a resonant oscillating circuit on a pulsation w, N1 and N2 in an oscillating circuit of pulsation 2w, etc. (it will be here noted that it is not necessary for the high frequency fields of pulsation w, 20:, to succeed in this order or be juxtaposed along the beam; they may for example be separated by spaces free from fields).

The operation and regulation of this collector of energy are based on the following observe tions:

As appears from the generalities at the outset, the maximum efficiency is obtained when the valve is regulated in such manner that the greater part of the electrons (if not the whole) issuing from the system of control in the course of a period, pass at the same instant through the collector. The collectoris thus excited by impulses of pulsation 10. On the other hand, it is well known that impulses of pulsation to permit oscillatory system of pulsation no to be excited. It will thus be easily understood that by acting for example on the shunt impedances of the various oscillatory circuits of the above collector it is possible so to arrange that practically the whole of the energy transported by the beam appears in the resonant circuit of pulsation o, whilst there appear in the oscillating circuit of pulsation 2m, 3w only the energies just sufiicient suitably to excite the system of. control according to the invention. The valve having to act as a generator for a certain frequency corresponding to w, it is useless and even injurious for an amount of energy greater than that which is necessary for the control to be taken from the beam and appear in the circuits tuned to 2w, 30.).

Referring to Figures 5, 6, and 7, there will now be described by way of examples, various modifications according to the present invention of auto-oscillator transit time valves provided with systems of control and with collectors arranged as described.

The valve illustrated diagrammatically in Figure is a velocity modulation valve and with drift conversion in a space free from field. It is provided withonly the control electrodes A, B1 and B2 and outlet electrodes M, N; and N2; that is to say, that for the control and the taking of ener y, only two fields in each case are caused to act, in accordance with what has been stated above these two fields which are juxtaposed resonating on 'w and 2w. I

The rhumbatrons R1 and R4 are regulated to resonate on 2w.

The rhumbatrons R2 and R3 are regulated to resonate on w.

To obtain the maximum efficiency of the valve, the shunt impedance of R3 is adjusted so that U=Uo and R4 is adjusted to a value just sufficient to enable the energy necessary to excite R1 to be taken from the auxiliary collector so as to produce between A and B1 the oscillating field with pulsation2w.

The transfer of energy between the corresponding rhumbatrons will take place for example through the lines Z1 and Z2 and magnetic coupling loops b1b"1, b2b2.

The energy which can be employed at the pulsation to will be transmitted to the load by a line 13 and the loop be located in the principal collector of energy R3.

Figure 6 illustrates diagrammatically a velocity modulation valve by longitudinal control and with deflector field. The control and. collector sys-, tems as also the coupling systems are similar to those of the preceding valve.

The rhumbatrons R1R2R3 and R4 are raised to the same continuous current potentials Uo; P at the potential Up 0 is the electrode collecting electrons and H at the continuous current potential UH is the deflecting electrode.

Figure '7 illustrates diagrammatically a velocity modulation valve with retarding field; the grouping of the electrons is effected by total reflection and the system of control operates at the same time as a collector of energy. This is composed essentially of two rhumbatrons R1 and R2 of pulsation 2w and raised to the continuous potential U0; P is the reflectingelectrode, raised to a negative potential with respect to the cathode K. The electrons coming from K, are modulated in velocity by the system RiRz grouped in the space R zP and traversing afresh the system R1R2 where they give up their energy.

The adjustments of the valve must be such that the energy given'up is effected almost solely to the advantage of the electromagnetic field of R2, Whilst there is produced in R1 only a slight exchange of energy between the electrons returning and the electrons passing out.

It is known that valves with retarding fields and with sinusoidal control have a maximum theoretical efliciency lower than that of drift space valves. This is due principally to the restrictions of phase and of non-reflection of the electrons by the high frequency field, which do not exist in drift space valves. If, owing to the addition, according to the present invention, of several high frequency fields, it is possible to improve the grouping of the electrons and to be left free to a certain extent of the restriction of phase, the restriction of non-reflection of the electrons by the high frequency field still persists. The latter results in that U /U0 is at the most of the order of 0.70 instead of 1, and thus the maximum efiiciency is of the order of 50% instead of 73%.

The invention is naturally capable of other modifications without departing from the spirit of the invention.

What we claim is:

1. Electron beam tube comprising, a composite input resonator for producing a periodic velocity variation of the electrons and constituted by at'least two side-by-side elementary resonators each comprising a group of two grids between which there is connected a resonant circuit, means connected to said input resonator providing a drift space for causing the velocity modulated electron beam to form into bunches while traversing this space, and an output resonator connected to said means for receiving the radio frequency energy of the bunched electron beam comprising a resonant circuit tuned to a fundamental frequency with means for connection to a utilization circuit, the resonant fundamental frequencies of said elementary resonators being chosen respectively equal to the said fundamental frequency and harmonics thereof, where n is the number of elementary resonators.

2. Electron beam tube according to claim 1, in which any two of the successive elementary resonators comprise a common grid.

3. Electron beam tube according to claim 1, in which the output resonator is in the form of a group of elementary resonators of which the number and the electrical characteristics are similar to those of the input resonator, and coupling means between the elementary resonators the frequencies of which correspond to each other in the input and output resonators,

whereby the tube behaves as a generator of waves at the fundamental frequency.

4. An electron beam tube according to claim 1, in which the output resonator is in the form of a group of elementary resonators of electrical characteristics similar to those of the input resonator, each of the elementary resonators of the input resonator being coupled with a corresponding elementary resonator of the output resonator, with the exception of one at least thereof, from among those of which the resonant frequency is an harmonic of said fundamental frequency, and means comprising a sinusoidal voltage source outside the tube and coupling means between said source and said last mentioned res- 9 onator for externally exciting it by said harmonic frequency.

ROBERT V/ARNECKE. JEAN BERNIER.

REFERENCES CITED The following references are of record in the file of this patent:

Number 10 UNITED STATES PATENTS Name Date Litton A Dec. 8, 1942 Litton Dec. 22, 1942 Samuel Oct. 15, 1946 Mouromtsefi et a1. Nov. 19, 1946 Alford Aug. 5, 1947 Hansen et a1 Oct. 26, 1948

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