Both Aerial and Earth should be Carefully Insulated

Radio Record, Volume I, Issue 12, 7 October 1927, Unnumbered Page

Both Aerial and Earth should be Carefully Insulated

Reception will be Materially Improved

. An American authority makes out a case for thorough insulation of the earth "wire as well as the aerial. He says that the radio user who desires efficiency, volume, range, and selectivity ‘ cannot attach too much importance to insulation of the aerial and earth wire. As the collector of feeble radio impulses, the aerial is of supreme importance, and on a par with it, in carrying away the waves after they have been through the receiving apparatus, is the earth connection. An analysis of radio broadcasting will, very probably, explain this most clearly. The wave that is sent out , from a broadcasting station travels over an ever widening area, gradually becoming weaker and weaker as it goes hundreds or perhaps thousands of miles through more or less absorbing atmosphere and over imperfectly conducting ground, Sensitive Aerial. The receiving aerial may be pictured in the mind as the "fingers of the air." To make use of this feeble impulse, the aerial must be sensitive. Once the waves strikes the wire, it begins a journey to the receiver that may be as weakening as the projection from the distant broadcasting station. The main cause of this weakening is poor insulation. A point of poor in |

sulation is a point where there is a "leak." That is, the current is able to flow off the aerial wire and into the roof or the walls of the house. This involves a loss which manifests itself in weaker signals. Use Best Instlation, Impulses picked up by a distant receiver are so very minute that the most effective collective device possible should be used, and every possible method of insulation be utilised in order to give them a "clear track" into the set. When an aerial is on the roof, the lead-in should be held away by insulation from the sides of buildings, The lead-in should also be run through the wall or window with a porcelain tube or like insulation, To Avoid Losses, Inside the room short leads are best,

but regardless of whether the lead is long or short, it should be insulated just as well as the wire on the outside of the house or apartment. The popular theory that inside or outside wooden, stone, or brick walls will not deduct from the efficiency of an aerial is false, The radio listener who has his lead-in tacked to the surface of a building may not think that power is diminished, yet there is probably a loss here that is reducing his range and | selectivity. Even if the wire has an insulating covering it should not be run directly against a wall. , The very} proximity of the wall may cause a loss, Insulate Earth Wire. Aiter passing through the receiving instraments the signal currents flow into the ground, and here ,insulation is again highly important, ‘At first sight it,

seems unimportant by what path the impulses get into the ground. One would think that the more paths that were provided the better. This, however, is not the case. Only one earth should be provided, and that one the best earth ‘available, The important thing about the ground connection is that it have as low a resistance as possible. High resistance reduces the signal strength, The singular thing about radio ‘currents is that they do not follow the path of least resistance. The word resistance is here used in its technical sense of electrical resistance. They follow the easiest path, to be sure, but this is not neces-. sarily the path of least resistance. The easiest path for radio currents is the shortest path, We can, therefore, have the following queer condition: Suppose. a radio receiving installation has two earth connections, one near the

receiver and the other at some distance from it. Most of the signal current will flow into the ground through the nearer earth connection. Very little of it will flow through the distant earth connection, If, therefore, the ncarer earth connection happens to have a large resistance, the signal strength will be reduced. Now, if the nearer earth is removed the current must flow through the distant earth connection-it has nowhere else to go, and if the resistance of this ground is low the signal strength will be greater than when there were two grounds, The practical application of all this is to be sure to support the ground wire on insulators up to the point where it is connected to ground. Water pipes are about the best thing on to which to connect t's ground wire, and the connection at this point should be as positive as possible, »