MEASURE YOUR AERIAL

Manawatu Times, Volume LIII, Issue 6613, 18 May 1928, Page 4

MEASURE YOUR AERIAL

It is very often desirable to know what the natural electrical length of an aerial is. The only way to measure the length accurately is by means of a wave meter—and this is beyond most people, who are interested in radio. But there is a way to find approximately the electrical length, and this is good enough for most people. The rule for single wire aerials': Take the combined length of aerial and leadin from end of wire to set, divide by three, and multiply by 4.8, or, for an inverted L-type using four wires, multiyly by 4.5. This gives the approximate electrical length in metres. For example:— A singlo wiro aerial is 100 foot | long, has a lead-in wire 50 feet long. AVh.it is its electrical length. 100 plus 50—equals 150, which is the total length in .feet. 150 divided by .3—equals 50, total actual lineal length in metres.

50 multiplied by 4.B—equals 240, which is the electrical length of the aerial in metres, or, the wave-length the aerial will receive without additional adjustment or tuning. This aerial will not receive below 240 metres with the ordinary broadcast receiving set, although the aerial will serve quite well for ultra-short-wave reception with a short-wave receiving sot.