electronic aerial switch - simple and loss-free

electronic aerial switch Many radio- and TV-amateurs have often wished they had a simple means of switching from one aerial to another. The normal solution is to do this by means of plug and socket arrangements, because a loss-free switch for changing aerials is not as simple as it sounds. This article shows that aerial switching is possible without introducing losses into the signal paths. The problem revolves around the losses caused by a mechanical switch. At relatively low frequencies (medium- and short-wave) such losses are not serious, but in the VHF and UHF bands they become a nasty problem. Even so, the most obvious and by far easiest way of selecting one of a number of aerials is by means of a mechanical switch as shown in figure 1. There is, however, a means of obviating the disadvantages of a mechanical switch at high frequencies and that is by using PIN diodes which are ideal for this purpose. PIN diodes What are PIN diodes? Briefly, they are special switching diodes o...