MARCONI'S BEAM

Radio Record, Volume I, Issue 21, 9 December 1927, Page 16

MARCONI'S BEAM

_ FADING-A BIG PROBLEM ARE SUNSPOTS RESPONSIBLE? Guglielmo Marconi told the Institute of Radio Engineers and the American Institute of Electrical Engineers in New York recently that he has succeeded in girdling the globe with a radio beam, the principle of -which he demonstrated just five years ago before a joint meeting of those two electrical societies. In 1922 he had a crude framework erected on the platform to show how he believed the beam would work. He then showed lantern slides of powerful beam stations. Senatore Marconi said fading was the big problem in connection with radio, especially on short-waves. He pointed out that fading has been a marked feature of long distance radio, especi-’ ally when short waves were employed, and although in his.experience fading appeared to be worse on wave-lengths between 200 and 1000 meters it often proved to be serious on the very short waves utilised by the beam system. "Tading has always been more frequent and more severe on the Eng-land-Canada circuit than on any of the others," he said. "It may be noticed that our Canadian service is also our shortest distance service, that it is mostly across the sea and that the Canadian station is the one which happens to be nearest to the north magnetic pole. DO SUNSPOTS CAUSE FADING? "Tt frequently occurs that when the Canadian communication fades out for some hours on end, the other services to Australia, India, and South Africa, which use similar wave-lengths, continue working with undiminished efficiency. It has also been noticed that the times of bad fading practically always coincide with the appearance of large sunspots and intense aurora borealis, usually accompanied by magnetic storms, and at the same periods when cables and land lines experience difficulties or are thrown out of action. "We have also frequently noticed that during these periods signals could be received on a shorter wave-length —

ae than the one usually employed, often on a i16-metre waye when a 26-metre waye would not come through. PECULIARITIES SF WAVE: LENGTHS. "As is now generally known very short waves of 16 metres and under can be better received at long distances by daylight and in summer time than during winter or at night, and we also know that very long wayes are not affected by daylight." Marconi said short wayes would solve congestion in the ether. "Tf we assume that long waves may be classed between 5000 and 30,000 metres, and short waves between 5 and 100 metres," he said, "then, by applying the basis of a rule proposed for the consideration of the International Radiatelegraph Conference at Washington, we find that 8700 wave-bands. or channels will be practicable and permissible for the short-waves, but only 90 for the long waves."