Abstract
Sir NOEL ASHBRIDGE, controller of the Engineering Division of the B.B.C., gave an account of “Short-Wave Broadcasting : Ten Years Technical Progress”, in the Overseas Service of the Corporation on December 17. Sir Noel said that it is about eleven years since the B.B.C., in spite of inconclusive reports on the existing service, decided that an attempt should be made to build up a regular short-wave service to the countries of the British Empire, trusting to an improvement in both transmission and reception to make it justifiable. The bare principles on which the first station was designed did not differ in essentials from the much bigger stations which several countries are operating to-day. Wavelengths in several groups within the limits of 13 to 50 metres are still used, except for the 100-metre transmissions to Canada, which are only used to overcome somewhat special conditions. Again, the principle of transmitting on directional beams, taking various parts of the world in turn, following the clock, still more or less applies to-day. No striking new invention has arisen to revolutionize the technique, but a great deal has been learned about the design of aerials, and how to construct them so that they radiate a beam of the right width and depth and as nearly as possible at the right angle to the earth, so that they will be reflected back to earth by the ionosphere, and arrive in that part of the world where they are intended to be received. The first experimental transmitter used only one wave-length, and the new station completed ten years ago used eight wave-lengths. We are now using no less than forty-four. The hours of transmission, too, are strikingly different ; the first station with its two transmitters sent out twenty-three transmitter hours per day ; but now the number of transmitter hours per day is more than three hundred and fifty-six. There was only one language used with the first station, as against nearly fifty at present.
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Short-Wave Broadcasting : Transmission. Nature 151, 17–18 (1943). https://doi.org/10.1038/151017b0
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DOI: https://doi.org/10.1038/151017b0