Aha, OK. So what is the antenna impedance? who knows you just have to mach it. Aha Ok. and how do we match it? mmmm who knows. Thanks BridgeCom Systems Very clear answers, right to the point.
NO! Your Tx output impedance is very much lower than 50 Ohm (unless you have a really old valve Tx!) Ok, the 'maximum power theorem' correctly says that to get the maximum power transferred from source to load you need to match source and load impedances. Now think of 'matching' a load to the mains supply, impedance probably an Ohm or less. Yes, you will draw many kiloWatts - but not for long! A breaker will pop or a wire will melt. It is the same with a Tx. It will fault if you match it's output impedance. Tx's have a 'rated load impedance', probably 50 Ohm. Modern Trx will survive if the load is bigger than that but will be destroyed by lower loads impedances (counting 1..2..3..Bang!)
NO again! If the antenna is 50 Ohm and so is the feeder then the length of the feeder isn't important for matching. It is 50 Ohm all the way! Also, mismatching impedances do not ALWAYS result in "Complex Impedances". A purely resistive but mismatched load on a 50 Ohm feeder will present a different impedance depending on it's length but at multiples of an electrical length of 1/4 wavelength that will be purely resistive, not complex. Even a reactive load will present a purely resistive impedance at some feeder lengths. If you want to understand what happens, please get to grips with the 'Smith Chart'. Perhaps the easiest way to do that is to use the 'SimSmith' app. I think it is time I stopped watching this presentation. Life is too short! 73 de M0PTB PeteS
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