MEASURE YOUR AERIAL

Horowhenua Chronicle, 22 May 1928, Page 2

MEASURE YOUR AERIAL

It is very often desirable to know wliat 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 lead-in from end of wire to set, divide by three, and multiply by 4.8, or, for an inverted L*type using four wires, multiply by 4.5. This gives the approximate electrical length i* metres. For example:— A single wire aerial is 108 feet long, has a lead-in wire 50 feet long. What is its electrical length. 100 plus 50—equals *l5O, which is the total length in feet. 150 divided by 3 —cquaW 50, total actual lineal length in metres. 50 multiplied by 4.8 —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 , 24A metres with the ■ ordinary ■ hiioadsast receiving set, although the aerial will serve quite well for ultra-short-wav® reception with a short-wave receiving set.