DISTORTION ON RADIO

Press, Volume C, Issue 29656, 28 October 1961, Page 13

DISTORTION ON RADIO

Vertical Aerial Recommended

Vertical aerials should help people outside Christchurch, who were getting distorted reception from Christchurch radio stations, the senior radio inspector (Mr J. R. Dolan) said yesterday. In response to a request from the Ashburton Chamber of Commerce, he had been examining reception conditions in the town. “In Ashburton, as In many other, districts around Christ - church, Including places as close as Ranetora, there is often distorted reception from the Christchnreh station*. especially SZB," said Mr Dolan.

Reception from the etation would be ouite normal when suddenly the aoeech or music would become greatly distorted, with the speech almost nr ouite unintelligible, said Mr Dolan. “The cause is interference between the direct radio wave received along the eround and a wave bounced off the ionosphere. A vertical aerial will be much more efficient at bringing In the ground wave than the skv wave, getting rid of most of the distortion.” he said.

Nevertheless, there were disadvantages In a vertical aerial. A horizontal aerial usually tended to pick up much lees local interference for such things as household appliances or power-line coronas, and it was better for really long-distance reception. The recommended horizontal aerial was. strung between poles 40ft to 50ft aoart and 20ft to 35ft hi»h. A vertical aerial had the added disadvantage that it was susceptible to "rainsizzles” during certain heavy rains.

The inspectors had investigated 21 complaints of radio interference In Ashburton this year, and had compJeted all but one. Mr Dolan added.