Questions and Answers

Radio Record, 22 April 1938, Page 65

Questions and Answers

"WHIL" (Aucklaud): There are many factors which affect the exact size of an aerial for shortwave work-tov many to relate here, However. its there is a variation in the frequencies to be received on the usual commercial receivers some compromise must be made. By careful design of two coupling transformers and the connecting link between them, manufacturers have beep able to produce an aerial which will give excellent reception over all the shortwave bands in addition to. the broadcast band. A doublet aerial has a certain amount of directivity, so that it has to be erected in a certain direction in regard to the stations to be received, and if properly designed gives a great signal strength for frequencies around its own resonant frequency. Hence such an aerial will not respond equally well over much of a frequeney range. We TUDE TELELEP LETTE LELELELELELIELALEEELELERELEELERELELERE LEELA LALA

note the make of your receiver, and suggest that rou investigate the uerial made by these people,:as it is goud, "PERPLEXED" (Blenheim): Your arrangement of two aerials caunot be made to give better reception of say, the Americans. as the directions of the two, for one thing, are at right augles, so that whatever directional properties euch may have, the combination ix practically non-directional. Hach aerial is about the correet length to obtain the best results with your particular receiver, and cuudidly. we feel that either acrial alove will be best for your set. The region of 200 to 205 metres gives a better reception, as just about bere is the resonant f[requency of the combined aerials und nerial coil. You could try using one aerial as earth and the other as uerial-there might be an advantage. but otherwise use the NW-SE aerial for NE-SW reception, and the NIE-SW for NW-SE reception,