Radio Broadcast (May-Oct 1922)

Radio Telegraphy By GUGLIELMO MARCONI The most striking point in Senator Marconi's lecture before a joint meeting of the American Institute of Electrical Engineers and the Institute of Radio Engineers, held in New York City on June 20th, was the sugge; )n that the shorter wavelengths have been practically abandoned by experimenters and commercial interests. Due to recent advances in the radio art, especially the development of the vacuum tube, eflFective signalling on short waves is now possible. Mr. Marconi suggested that this will undoubtedly stimulate a great interest in American amateur radio circles which should result in further radio success. In speaking of his parabolic reflector system, he mentioned wavelengths of 15 to 20 meters, which, it would seem, are hardly possible for the average amateur worker, for the erection of a reflector 15 meters high covering an area 1 5 or 20 meters in diameter would involve a considerable expenditure. For the most part, American amateurs will have to devote their eflforts to short wave propagation without the use of the reflector, and it is interesting to note that, even prior to Mr. Marconi's lecture, American amateurs have made some very successful attempts to communicate by this method. Space does not permit us to reproduce Senator Marconi's entire lecture, but the following material covers the most salient points he made about radio telegraphy's past, present and future. — The Editors. HE first occasion on which I had the honor of speaking before the members of the American Institute of Electrical Engineers was of a very festive nature. It is more than twenty years ago, to be exact, onjanuary 1 3, 1902; (there was not then any Radio Institute in existence) and on that date, memorable for me, I was entertained by more than 300 members of your Institute at a dinner at the Waldorf-Astoria in this City. I was offered that dinner following my announcement of the fact that I had succeeded in getting the first radio signal across the Atlantic Ocean. Many men whose names are household words in electrical science were present, men such as Dr. Alexander Graham Bell, Professor Elihu Thompson, Dr. Steinmetz, Dr. Pupin, Mr. Frank Sprague, and many others. The function was one I shall never forget, and displayed to the full American resource and originality, as only forty-eight hours' notice of the dinner had been given, but what has left the greatest impression on my mind during all the long twenty years that have passed is the fact that you believed in me and in what 1 told you about having got the simple letter "S" for the first time across the ocean from England to Newfoundland without the aid of cables or conductors. It gives me now the greatest possible satisfaction to say that, in some measure, perhaps, your confidence in my statement was not misplaced, for those first feeble signals which 1 received at St. John's, Newfoundland, on the 12th of December, 1901, had proved once and for all that electric waves could be transmitted and received across the ocean, and that long distance radio telegraphy, about which so many doubts were then entertained, was really going to become an established fact. I propose to-night to bring to your notice some of the recent results attained in Europe and elsewhere and to call your attention particularly to what 1 consider a somewhat neglected branch of the art; and which is the study of the characteristics and properties of very short electrical waves. My belief is always that, only by the careful study and analysis of the greatest possible number of well authenticated facts and results, will it be possible to overcome the difficulties that still lie in the way of the practical application of radio in the broadest possible sense. A very great impulse has been given to radio telegraphy and telephony by the discovery and utilization of the oscillating electron tube or triode valve based on the observations and discoveries of Edison and Fleming, of those of De Forest and of those of Messiner in Germany, Langmuir and Armstrong in America, and H. W. Round in England, who have also brought it to a practical form as a most reliable generator of continuous electric waves. THE VACUUM TUBE As THE electron tube, or triode valve, or L valve, as it is now generally called in England, is able, not only to act as a detector, but also to generate oscillations, it has sup