GB715409A - Improvements in or relating to electronic high frequency signal translating devices employing wave transmission circuits - Google Patents

Abstract

715,409. Travelling-wave tubes. WESTERN ELECTRIC CO., Inc. May 6, 1952 [May 10, 1951], No. 11411/52. Class 39(1) [Also in Group XL(c)] A barrier electrode is inserted between two sections of a helix, or between two separate helices, in a travelling wave tube to intercept most or all of the electrons when the input signal is below a predetermined level; when the signal level rises sufficiently the transverse field component of the wave deflects the beam so that some electrons can pass the barrier electrode and give up energy to the output helix section or helix. In one form, Fig. 1, the gun has indirectly heated cathode 3, focusing electrode 8 connected to the cathode and supported by discs 11 from glass envelope 1, and accelerating electrode 9 connected to helix 13 via input coupling probe 17 and thence via output coupling probe 20 and lead 27 to battery 29. The helix is supported from the envelope by two or more ceramic rods 14 and the input and output coupling to waveguides 23, 25 is via probes 17, 20 and by pass capacities 9, 22; 21, 24. Loss material 12 disposed on rods 14 prevents wave energy from passing from the left to the right helix portion and serves as matching terminations for the helix portions. The electrons are focused by coil 18 or 19 on to barrier 15 connected to the helix by wire 16; the barrier 15 is disposed in the region of loss material 12 or slightly to the left of it. Thus the noise between input signal pulses may be eliminated and the noise distorted pulses reshaped to some degree when the device is used as a receiver or repeater in microwave pulse communication systems. In a modification, Fig. 3 (not shown), the beam is annular and passes outside two sections of helix separated by and connected to the barrier, the helix supporting rods being inside the helix and having loss material as in Fig. 1. The envelope is of metal and is slightly negative to the helix sections; the input and output guides are integral with the envelope. The input and output coupling devices each comprise a cylindrical electrode carrying a coupling probe connected to the helix, and co-operating with an outer annular electrode to form a by-pass capacity. The electrode leads are sealed through the envelope by glass beads. The beam is focused on to the barrier by magnetic and/or electro-static means, the latter taking place in the gun and comprising axial and perhaps radial fields.