A Radio Warning.

Star (Christchurch), Issue 19197, 10 October 1930, Page 6

A Radio Warning.

To the Editor. Dear Sir,—lt would be interesting to know where Mr Shipley gets his ideas about the range of radio stations. He states that increasing the power from 500 watts to 2000 watts would increase the range from 25 miles to 100 miles. As a matter of fact, the range of a station theoretically increases as the square root of the power, practically it is less than this. In this case a fourfold increase in pbsyer would mean only a twofold increase of range. Even supposing the power of 3YA were doubled, it would not mean that twice as many listeners would be served. Probably 90 per cent of the available listeners to 3YA are already within range of the station. TJie additional expense of doubling the range would not be justified by the small increase in listeners. Moreover, there are quite definite limits to the useful range of broadcasting stations. Beyond certain powers, the effectiveness is not noticeably improved, and atmospheric conditions play a considerable part. As far as the additional stations are concerned, I remember reading two years ago that the Radio Broadcasting Company had suggested that this same scheme should be put into operation, but the Post and Telegraph Department apparently sat on the idea, and are now putting it forward as their own. Reverting to the range question, I have seen figures adopted by the U.S.A. Federal Radio Commission which give ten miles as the effective high grade range of a 500watt station, eighteen miles for a 2000-watt station, and thirty miles for a 5000-watt station. This is vastly different from Mr Shipley's twenty-five and one hundred miles respectively, and presupposes the power is actually 2000 watts and not 1000 watts as it will probably turn out to be. On the other hand 3YA is already of 1000-watt power if we rate it along the English <M Continental lines. Listeners should be very wary abodl allowing the present station to be scrapped and new stations installed at enormous expense and with doubtful improvement.— I am. etc.. LICENSED LISTENER.