Foundations Of Amateur Radio

Foundations of Amateur Radio Today I'm going to talk about SWR or Standing Wave Ratio. As amateurs we use this term all the time, we expect to see it on a meter or display near our transmitter, we buy specific gadgets to measure it and often we seek to find the lowest possible SWR. As I've said in the past, the perfect antenna cannot exist, in the same way, a perfect connection, the feed-line, between an antenna and transmitter can also not exist. The perfect match is a 50 Ohm match, but a dummy load is a perfect match and its purpose is specifically not to radiate. So what's all this about then? Lets start in a swimming pool for a moment. Imagine that this pool is really long and skinny. Say 100m long and 1cm wide. Stand on one side and make a splash. The ripple of the water radiates from the source of the splash, you, to the other end of the pool. The end wall bounces the ripple back to you, and bounces back and forth until all the ripples have dissipated. Now, if you kept splashing about, and waves w