RADIO PHENOMENA

Otago Daily Times, Issue 23332, 26 October 1937, Page 10

RADIO PHENOMENA

fi SYDNEY SCIENTIST’S WORK ! * EXPERIMENTS VERIFY THEORY (From Our Own Correspondent) SYDNEY, Oct. 15. A remarkable instance of a scientific theory leading to prediction of "phenomena not previously known, but quickly verified by experment, is provided oy the recent work of Professor V. A, Bailey, professor of experimental physics at the University of Sydney. The theory is a new mathematical study of broadcasting interference or “-radio interaction,” popularly known throughout the world as the “Luxembourg effect," and first noticed in 1933. This consists in the superposition of the programme of a distant powerful station on broadcasts from another distance station, even when the wave lengths are very different. It was first explained by Professor Bailey, and then discussed in more detail by him in collaboration with Dr D. F. Martyn, research physicist of the Radio research Board. The phenomenon predicted by the new theory has been called “ gyro interaction.” The term means that this kind of interference is caused by radio waves which have frequencies nearly the same as the Joeal gyro frequency. Such radio waves have wave lengths of about 2PT metres.

The term “ gyro frequency ” is derived from the fact that an electron “ gyrates ” in the earth’s magnetic .fir’d, moving in spirals at the large rale of about 1,500,000 turns a second. In he, radio waves of similar fre4 1'-'ncy. the electric force oscillates to rnd fro 1.500,000 times a second. Such a wave would have a length rjf about 200 metres. Hence the name “ gyro ” interaction. While abroad recently Professor Bailey was able to test his theory through the collaboration of 10 broadcasting stations. About three dozen observers co-operated. On the second night of these experiments the predicted phenomenon of gyro int'rsction was observed.

One striking prediction verified by the experiments was that a power of one or two kilowatts (that of the ordinary domestic radiator), if radiated in the form of a 200-metre wave, would suffice to produce changes in the atmosphere at heights of about 6') miles, perceptible by interaction wilh another wave. This contrasts with the opinion generally held previously that observable interaction could be caused only by stations with powers icx'-eeding 50 kilowatts. ■ Another interesting prediction, indirectly confirmed by the experiments, is that a notable increase in interaction may occur as the frequency of the interfering station is made to pass through the value of the gyro frequency. That is, a kind of “resonance ” exists between a station and the earth's magnetic field. Eclating the steps of the theory’s evolution. Professor Bailey said: “ While acting as examiner for the University of London in 1933 I read a thesis by a distinguished radio re-search-candidate in Sydney. In the course of reflecting on this thesis I conceived an idea which offers a simple explanation of the so-called ‘..Luxembourg effect.’ This was that a powerful broadcasting station of about 200 kilowatts must be able to impress its modulation on the wave from another station when the latter wave is reflected from the ionosphere (or electrified region of the atmosphere) in the neighbourhood of the powerful station. The theory Dr Martyn and I evolved was in good agreement with most of the known facts of the interaction of radio waves. It indicated among other things that interaction is strongest when the interfering station has a long wave length, and that the effect becomes inappreciable for much shorter wave lengths. “Over a year ago, in attempting to develop a mathematical theory of the influence of several waves acting simultaneously, I discovered an inaccuracy in the earlier theory. This at first seemed of no great importance, but closer inspection showed that it concealed an unexpected and important conclusion. This was that radio interaction could be produced not only by high-power stations using a long wave length, such as 1500 metres, but also by low-powered stations using the lower wave lengths of the broadcast band, around 200 rhetres. The results of the experiments abroad strongly confirmed the Hew theory.”