An Ideal Aerial.

Radio Record, Volume II, Issue 14, 19 October 1928, Page 15

An Ideal Aerial.

Fe For Country Listeners. ‘WHAT do you consider an ideal aerial for a country listener?" asked a visitor to Wellington the other day. Up-country, where interference is not possible from a local station a long aerial is desirable, as the longer it is up to a certain point the better it will bring in the distant stations. A long aerial in Wellington, close to 2YA, renders it difficult to cut out the big station owing to the tuning being broadened by a long aerial. However, upcountry, away from a big station, this difficulty has not to be contended with. A good up-country aerial would be as follows :- Length, including the lead-in, 145 feet. Height above all obstacles (outhouses, fences, hedges, trees, etc.), 60 feet. Type of aerial, inverted L with the lead-in not brought in at a_ sharper nngle than 45 degrees to the aerial. Aerial wire; enamelled, seven strands of 21 gauge, or thereabouts, the leadin to be the same type of wire. Insulators; not fewer than four at each end of the aerial and so spaced that the aerial iteself is not closer than 10 or 15 feet from either mast. Halyards: ordinary galvanised clothes-line wire. Stays of masts; galvanised fencing wire or galvanised clothes line wire, with each stag "broken" by two insula{tors each about 25 feet apart. At least six stays to each mast.

Masts; straight wooden poles, tarred: at the foot where they enter the ground to prevent speedy rotting. Direction of aerial; not important, as so high an aerial has very little directional effect. An aerial less high should have the lead-in end nearest the direction of the furthermost stations which are most frequently desired. The aerial need not be horizontal, but if one end is higher than the other the lead-in end should be the lower. Lead-in to house; should be through a long porcelain tube, preferably pushed through a hole bored in the top of the window frame. The "earth"; if possible should be the nearest water-pipe to which it should be firmly soldered, and the joint then tightly bound with adhesive tape to prevent corrosion. The absence of a water-pipe can be successfully overcome by soldering thick copper wire on the inside bottom of two or three kerosene tins so as to join them together electrically. The kerosene tins should then be filled up with wood ashes or finelycrushed charcoal or coke, and then buried with 3ft. of earth above them ifter firmly soldering the earth-wire to each of them. The tins should be buried as close to the radio set as possible. An old piece of water-pipe may be stuck down into the centre of one of the tins and should project a few inches above the surface of the ground. Water should .be frequently poured down the pipe to keep the contents of the tin well moistened. A cork o£ wooden peg should be stuck into the top of the pipe to keep dirt from get{ing down and blocking the descent of the water. The earth-wire should be as heavy as possible and insulated if possible, Heavy insulated copper cable used in atreet electric light wiring makes an ideal earth-wire. The advantage of insulating the earth-wire is that it prevents weakening of signals in wet wea~ ther because the radio-frequency curvent prefers to take the shortest path to earth even though it affords a poor cireuit. Therefore with an un‘insulated earth wire a shorter path to earth is offered in wet weather by the eurrent straying off the earth wire ilown the dampness on the side of the house to the earth, instead of proceeding along the desired circuit, which may be a trifle longer but much better. The earth-wire should be kept well apart from the lead-in wire where they enter the house.