Ultra Short-Wave Wireless Telephony

Radio Record, Volume V, Issue 27, 15 January 1932, Page 6

Ultra Short-Wave Wireless Telephony

Important Demonstration by Marconi qT the presence of representatives of the Italian Government, an ofiicial demonstration took place on November 20 in Italy between Santa Margherita Ligure and Levanto-a distance of 25 miles-of the new Marconi quasi-optical, ultra-short wave radiotelephone system. The wavelength used was only 50 centimetres (the same as that employed in the previous demonstration recently carried out between Santa Margherita Ligure and Sestri Levante over a distance of 11 miles), corresponding to the enormous frequency of six hundred million cycles per second. The success of the demonstration was all the more complete because, although the range had been increased from 11 to 25 miles, the margin in the signal strength was such as clearly to indicate to all present that apparatus used was capable of covering a considerably greater distance. In an interview granted immediately after the demonstration to representatives of the Press, his Wxcellency the Marchese Marconi made the following interesting statement :- "Since 1896, when I was already experimenting with wavelengths of 20 centimetres, I had no doubt in my mind but that the short waves, which are called quasi-optical because they behave very like the waves of visible light, would one day come into use for commercial communications. The results of those very early tests were confirmed by the more recent experiments I carried out at Leghorn during the World War using a wavelength of 50 centimetres. However, nobody, myself included, had then succeeded in producing ultra shortwave apparatus sufficiently powerful, economical, and reliable to justify its immediate use for public telephone or telegraph services over suitable distances. "During the last six months, my assistants, particularly Mr. G. A. Mathieu, and myself have been concentrating our efforts toward a commercial solution of the problem, and many unexpected and valuable discoveries have been made, I would therefore ask you not to consider this demonstration as a mere scientific experiment, but as a test of a new practical and commercial radio-system which will very shortly be used for public services in Italy. Owing to its simplicity the new system is very moderate in price and in running costs; it will thus soon afford to the inhabitants of many small islands scattered in the Mediterranean a reliable telephone service which they could not, heretofore, enjoy in consequence of the high cost of the submarine cable telephone installation." Requested to state whether it was correct that the application of this "quasi-optical" wave was strictly limited to very short distance communications, Marchese Marconi added: "Well, at the present stage of our knowledge I do not anticipate a reliable range of more than about 100 miles; but this is of course a very useful range in itself and could be very greatly increased by making use of relays or repeaters wherever possible,"