ULTRA SHORT WAVES

Evening Star, Issue 22572, 13 February 1937, Page 4

ULTRA SHORT WAVES

SOME NEW POSSIBILITIES Mr S. Gordon Taylor, speaking from the Schenectady short wave stations W2XAD and W2XAF recently, compared the present state of ultra short wave transmissions to - that of short wave communications 10 or 12 years ago. “It is now realised,” he said, “ that within a few years ultra short waves will probably equal in importance the broadcast waves and the short waves which are now being utilised to such excellent advantage. So far as utility is concerned the primary difference between our present short waves and those wavelengths below 10 metres lies in the much more limited transmission distance ranges of these ultra short wave lengths. In general, they can he depended upon to reach out only 50 to .100 miles, but can provide good signals over this small area with very low power. “ This short distance range, of course, imposes one limiting factor on the utilisation of very short waves, but, on the other hand, it likewise gives them a distinct advantage. At tho present time a moderately powered broadcast station operating on a wavelength of, say, 31 metres, has a worldwide distance range, and therefore no other transmitter can be operated on the same frequency without causing interference. On the other hand, a station operating on a wavelength in the vicinity of five metres, for. instance, could probably operate on the same frequency with hundreds of ' other stations throughout the- world, spaced not closer than approximately 300 miles apart, with no interference suffered by any station or any listener. In the present radio set-up there are _ many services which are purely local in nature, yet, due to long-distance characteristics of the longer waves which they now use, are regularly, heard hundreds and even thousands of miles away. “ A typical example of this condition is found in police radio. One can sit at a short wave radio set in New York City, for instance, and hear police stations in cities throughout the country, issuing instructions to their stations. < Np,fc ; -only is this wasteful of our radio facilities, but; at times it is confusing to the police cars which are carrying receivers, because another police station, hundreds of miles away, operating on the same frequency as their own, may cause ,serious interference. The other types of services for which the very short waves are most suitable are numerous. “The small size and low power ‘requirements for transmitters make them highly practical' for, all sorts; of portable and mobile communication work. Some of the applications are relay broadcasting, facsimile transmission, disaster relief, and street’, traffic direction and supervision. -These, plus television and high-fidelity broadcasting, represent .just a few of the practical applications of the ultra-short waves that have been successfully tried. In addition to these, there arc innumerable others which will be proven practical as time goes on. Then when this field has been developed there will be now worlds to conquer in tho still shorter wave lengths—the micro waves. Hero entirely new possibilities of secret air communications are opened up. It would take nothing less than a Jules Verne to forecast the possible developments in this field.”