GB470805A - Improvements in or relating to very high frequency receiving and detecting apparatus - Google Patents

Abstract

470,805. Cathode-ray tubes ; detectors. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Dec. 31, 1936, No. 35891. Convention date, Dec. 31, 1935. [Classes 39 (i) and 40 (v)] Detectors for ultra-short wavelengths preferably below 10 cms. comprise means 6 for producing an electron beam 10 directed towards receiving anodes 7 ... 9 and signal-responsive means 23 between the means 6 and the anodes 7 ... 9 to vary the speed of the electrons in accordance with the signals and so to vary the deflection of the beam by a constant, transverse, electric or magnetic field 31. In the absence of the signals, the beam proceeds as at 32 to the central anode 8 ; the signals increase or decrease the curvature of the beam as at 34, 33 causing it to fall on the interconnected anodes 7, 9, the signal modulation appearing across a resistance connecting the anodes 7, 8 and being applied to an audio-frequency amplifier 36. The means 23 comprises an antenna 25, 26 extending through the envelope 30 of the discharge tube and connected to transmission lines 35 which extend along the beam 10 and carry electrodes 27 surrounding the beam. The electrodes 27 are in pairs of closely adjacent, coaxial rings, one connected to each line 35 and the pairs are spaced apart along the lines 35 at distances equal to a multiple of a half wave. The velocity of wave propagation along the lines is made approximately equal to the electron speed in the beam 10, the lines 35 being straight or having inductive turns as shown, and the pairs of rings 27 produce cumulative changes in the electron speed according to the incoming signal. In a modification, the beam is deflected through 180‹, the electrodes 27 and deflecting magnetic field act simultaneously on the electrons, and the lines 35 and envelope 30 are, curved semicircularly.