US2087737A - Amplifier circuit organization, especially for short waves - Google Patents

Description

Source 0/ R431 0 v fieyueng Int/y] Magnei'ic Field W. RUNGE Fi'led' Dec. 19, 1935 July-Z0, 1937.

AMPLIFIER CIRCUIT ORGANIZATION, ESPECIALLY FOR SHORT WAVES CONSTANT MAGNET/C FIELD Anode Freyaeng [fie/2y v INVENTOR.

WILHELM RUNGE:

ATTORNEY.

Patented July 20, 1937 UNITED STATES AMPLIFIER CIRCUIT ORGANIZATION, ESPE- CIALLY FOR SHORT WAVES Wilhehn Runge, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic in. b. H., Berlin, Germany, a corporation of Germany Application December 19, 1935, Serial No. 55,138 In Germany January 29, 1935 6 Claims.

The present invention is concerned with an amplifier circuit, and particularly a magnetron circuit for use with extremely (ultra) short waves wherein the discharge is influenced by a separate radio frequency control magnetic field.

Amplifier arrangements are known in which magnetrons with a simple split anode are used and in which in parallel to the main magnetic field whose sense coincides with the axis of symmetry of the electrode system there is superposed an alternating magnetic field for the control of the discharge current. For the generation of these alternating fields recourse is had to cylindrical coils which are mounted in coaxial relation to the anode axis. (Note Patent 1,523,776.)

Now, these circuit schemes involve the drawback that for the control of the discharge process comparatively intense alternating magnetic fields are required. Conventional arrangements, for purely geometric reasons, are unsuited for the amplification of short waves, for the number of turns of the control coil cannot be diminished below one turn or spiral. However, such .a single turn being located outside the discharge vessel is of such a large diameter that it will be possible only with the use of large currents to generate the magnetic field required for the control action which is required.

The idea underlying the present invention is to use a singly-split (or simple-split) anode and to cause the control current to flow through the very anode. Since the anode current is comparatively small, currents of low intensity will suffice for the production of the controlling field. 'Ilie force-lines of this control field are directed parallel to those of the main field. The latter will conveniently have to be adjusted in such a way that the working (static) point, in the absence of excitation, comes to lie in the middle of the drooping branch of the tube-current, magnetic-field characteristic. The alternating magnetic field will then have to be varied only inside limits in which a slight increase in the field intensity will occasion a marked decrease or increase in the plate current.

With the anode would be connected, upon both sides of the split, two parallel wires which are united with the separate control (master) source. The said wires or line should suitably be so proportioned that the anode comes to lie in a current loop (anti-node) of the parallel wire system. By suitably dimensioning the characteristic impedance of the latter, it will be quite easy to obtain the desired current strength in the anode clip, seeing that wattless power is concerned.

To derive energy a distinct output circuit could be connected between the center of the anode and the cathode. Where ultra-short waves are dealt with, it will be preferable to dispense with a special parallel resonance circuit and to use the natural capacitances between the electrodes together with the inductance of the electrode connecting leads to act as elements in an oscillatory circuit.

In an amplifier circuit organization of the kindhere disclosed, it will, of course, be necessary to so arrange the leads which connect the anode and. the cathode with the load circuit in reference to the leads which introduce the control current of a separate source into the system that both magnetic and electric couplings between control (master) circuit and load circuit will be safely avoided. Since the alternating magnetic field is parallel to the constant field, all of the lead-ins brought to the consumer or load. circuit must be placed in a plane laid through the tube axis.

Figs. 1 and 3 are embodiments illustrating the basic idea of the invention, and Fig. 2 is a curve explanatory of the operation ofthe circuit arrangements.

Referring to Fig. 1, A denotes the anode and K the cathode of a magnetron containing a simple split anode. United with the anode upon both sides of the split are two parallel wires L1 and L2. Associated with these wires, at a voltage node S1 (in reference to the oscillations to be excited) is a separate radio frequency control (driver) source St which causes a current to flow through the anode, the latter, in turn, being placed in an anti-node or loop of current in the parallel wire system. This current will set up an alternating field M1 at right angles to the plane laid through the drawing, in other words, parallel to the main magnetic field. It is important to so dimension the main field M1 that operation takes place just in the steepest part (M2) of the anode-current, magnetic-field characteristic, (see Fig. 2). This is done with the end in View to minimize the radio frequency currents required for the control of the discharge process. The useful or load circuit LC is located between the cathode K and the electrical, and at the same time geometric, center Z of the anode A. In the lead brought to the i oscillatory circuit, between Z and L, C is included the source of anode voltage Ua.

What is fundamentally involved here is an emission-current control action as can be seen from the characteristic in Fig. 2.

In Fig. 3 a circuit organization is represented which is particularly suited for the production of ultra short waves. Similar reference letters indicate similar elements. The'separate master source St is here connected in a potential loop S2 of the parallel wire system by way of condensers. A separate useful circuit comprising a concentrated or lumped inductance and capacity has here been dispensed with. The natural frequency of this system is essentially determined by the capacity CAK of the electrodes A and K, and the inductance, which, on the one hand consists of the piece of parallel wire line L1, L2 located between the anode and the first voltage node, and, on the other hand, of the return wire Lr. The said portion of the parallel wire system is then traversed by the master energy in phase opposition and by the useful energy under inphase condition seeing that so far as the useful circuit is concerned, both conductors may be regarded as being connected in parallel.

What is claimed is:

1. A magnetron circuit comprising an evacuated envelope containing within it a substantially circular anode having a single longitudinal slit therein, a central cathode, a magnetic field surrounding said envelope, a pair of lecher wires connected to the two ends of said slit, and a source of radio frequency energy coupled to said lecher wires at voltage nodal points whereby energy from said source flows over said lecher wires and traverses said anode.

2. A magnetron having a cathode and a concentric cylindrical anode with a single slit parallel to its axis, an output circuit including a source of potential between said anode and cathode, a'direct current magnetic field parallel to said axis and adjusted with respect to said source of potential to bring the anode current to a value such that the rate of change of anode current with magnetic field is substantially maximum, a

two-conductor wave transmission line connectallel to its axis, an output circuit including a source of potential between saidanode and cathode, a direct current magnetic field parallel to said axis and adjusted with respect to said source of potential to bring the anode current to a value such that the rate of change of anode current with magnetic field is substantially maximum, a two-conductor wave transmission line connected to the two sides of said slit, and a source of alternating current energy coupled to nodal points on said line for setting up currents in said line which traverse the circumference of said anode, whereby there is produced an alternating magnetic field parallel 'to said axis for controlling the current in said output circuit.

4. A magnetron having a cathode and a concentric cylindrical anode with a single slit parallel to its axis, an output circuit including a source of potential between said anode and cathode, a direct current magnetic field parallel to said axis and adjusted with respect to said source of potential to bring the anode current to a value such that the rate of change of anode current with magnetic field is substantially maximum, a two-conductor wave transmission line connected to the two sides of said slit, means for setting up standing wave currents in said line which traverse the circumference of said anode where- .by there is produced an alternating magnetic field parallel to said axis for controlling the current in said output circuit, said output circuit including as a portion thereof a part of said transmission line with its two conductors in parallel relationship for the output current.

5. A magnetron having a cathode and a con centric cylindrical anode with a single slit parallel'to its axis, an output circuit'including a source of potential between said anode and cathode, a direct current magnetic field parallel to said axis and adjusted with respect to said source of potential to bring the anode current to a value such that the rate of change of anode current with magnetic field is substantially maximum, a two-conductor wave transmission line connected to the two sides of said slit, means for setting up standing wave currents in said line which traverse the circumference of said anode wherebythere is produced an alternating magnetic field parallel tosaid axis for controlling the current in said output circuit, said output circuit including a condenser and an in-- ductance in parallel relationship'and a connection which is adjustable over said anode.

6. A magnetron having a cathode and a concentric cylindrical anode with a single slit parallel to its axis, a source of potential, a connection from the negative terminal of said source .to said cathode, a connection from the positive terminal of said source to the potential nodal points of two conductors connected to the two sides of said slit, a direct current magnetic field parallel to said axis and adjusted with respect to said source of potential to bring the anode current to a value such that the rate of change of anode current with magnetic field is substantially maximum, a source of radio frequency energy coupled to said two conductors at voltage loop points, the capacitance between said cathode and anode together with the inductance of the connections from the positive and negative terminals of said source of potential to the electrodes of said magnetron constituting a tuned circuit to determine the natural frequency of said magnetron.

WILHELM RUNGE.

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