Ultra-Short-Wave Radio Research

Abstract

Two papers, communicated by the General Electric Co.'s research laboratories at Wembley, were read to the Radio Section of the Institution of Electrical Engineers on January 4 by Mr. E. C. S. Megaw. The first paper gives a critical summary of the existing knowledge of electronic oscillations. The methods of their production are outlined and their applications to radio communication are described. Using these oscillators and parabolic reflectors, Beauvais obtained in 1930 a maximum range of telegraphic transmission of about 25 miles from the top of the Eiffel Tower. In the Dover-Calais demonstrations of the International Telegraph and Telephone Laboratories (March 31, 1931) duplex telephony was achieved over a similar distance. In the second paper, possible methods of utilising magnetrons to generate short-wave oscillations are indicated and the more important of the results obtained by previous workers are described. Experimental investigations were undertaken to discover the relations between electron and dynatron types of oscillation. For electronic oscillations it was found that the experimental results are entirely in agreement with theory in those cases where it is applicable. The investigation of the simple dynatron oscillations showed that the static characteristics exhibited a negative resistance effect. During oscillations it was found that the anode current may exceed the original total emission current. This is considered to be due to the bombardment of the filaments by electrons which return to it with considerable velocity. The shortest wave-length obtained by means of dynatron oscillations was about thirty centimetres. At this wave-length the power attainable was about a tenth of a watt. It is concluded that for wave-lengths less than about fifty centimetres electronic oscillations give the greatest output.