GB477668A - Improvements in or relating to electron discharge devices and arrangements for use on very short waves - Google Patents

Abstract

477,668. Cathode - ray tubes and circuits therefor. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE. March 4, 1937, Nos. 6464, 6465, and 6466. Convention dates, March 4, 1936, April 6, 1936, and April 14, 1936. [Classes 39 (i) and 40 (v)] An electron-discharge device for the amplification and generation of very high frequencies comprises an electron beam which is deflected for control purposes transversely with respect to its direction of projection, and which is caused to give up its energy of transverse movement by electrostatic influence on a second transverse field through which it passes. The beam may pass between the output electrodes of a " coupling out " system which are influenced electrostatically by the beam. The beam itself does not strike the output electrodes but proceeds to a collecting electrode not carrying a high-frequency voltage. In the form shown in Fig. 3 an electron beam generated by cathode K and anode A is deflected by plates P, P1 and passes between the output electrodes Q, Q1, to a collector F. An amplified induced current flows in a tuned circuit between Q and Q1 having the same frequency as that between P and PI, but differing in phase by an amount varying with the beam velocity. To generate oscillations the plates P, P1, Q, Q1 are coupled together in correct phase, for example by a tuned Lecher wire system within the device, bridged at certain points to eliminate the fundamental. Alternatively, a second electron beam travelling in the reverse direction may produce backcoupling, as shown in Fig. 5. Here the primary beam E1 is deflected by plates P, P1 and induces amplified voltages on plates Q, Ql which deflect the reverse beam E2 so as to induce further voltages on plates P, P1. Tuned circuits S1, S2 connect the plates. The same principle may be applied to a cascaded amplifier, shown in Fig. 6. The input voltage applied to plates P1 deflects the primary beam E1, so as to induce amplified voltages on plates P2. A second beam E2 is deflected by plates P2 and induces voltages on plates P3, which are similarly transmitted to output plates P4, by a third beam E3. The collecting electrode for each beam may be the anode of the gun system producing the next beam; if these collecting electrodes are made secondary electron-emitting each beam may be produced by secondary emission from the preceding beam and the intermediate cathodes K2, K3 may be dispensed with. Back-coupling is prevented by screening or by neutralizing condensers between the first and successive pairs of plates. The final stage may be biassed to act as a rectifier. The beams need not be coplanar. In further modifications, the " coupling out " field may be transverse to the direction of deflection, as shown in Fig. 8, in which the beam E moves into and out of the field between the plates P3, P4. Two sets of plates may be provided, one on each side of the beam so as to utilize both halves of the beam oscillation. As shown in Fig. 10, the pairs of plates P<1>3, P<1>4, P<11>3, P<11>4, may be separated by a thin metal screen S which divides the resting beam into halves. If the beam rest in the centre of the plates, the induced voltage will have double the frequency of the deflected beam, and this fact may be utilized in a frequency-doubling device. By shaping the plates, the induced voltage may be given a sinusoidal, square or any other desired wave-shape. A number of such plates may be arranged in a linear or circular path and the beam deflected between them so as to produce frequency multiplication of high order. Magnetic fields may be used to deflect the beams. Intensity or velocity modulation may be applied to the beam. At very high frequencies the effect of the finite transit time of the electrons may be reduced in a known manner by dividing the plates into a number of pairs in the direction of the beam and cross-connecting them.