On Friday, July 17, 2020, 10:03:24 PM EDT, Fred Jensen <k6...@foothill.net> wrote:
> No antenna has, at any time, anywhere in any of our lifetimes, been > "tuned" by an "antenna tuner." Unless the "tuner" is simply a broadband transformer, I might agree. But if the "tuner" is an LC network, like an adjustable L network, T network, Pi network, or a linked-coupled network, then I strongly disagree. A tuner is a 2-port network. A transmission line is also a 2-port network. Both networks obey reciprocity, meaning that what you do to one port of the network will have a direct influence on the opposite end. That being said, if an antenna exhibits a complex impedance at our frequency of interest, and that behavior can be corrected (brought to resonance) by the application of a particular value of reactance at the antenna's feedpoint, then that application of reactance can, for reasons of convenience, be made at the "shack end" of the transmission line. As such, the "tuner" in the shack is really "tuning" the antenna! There's no "magic" involved here -- just a simple understanding that things that are connected together actually behave like they're connected together. A transmission line doesn't isolate the shack from the antenna: It couples them together with the highest degree of efficiency we can muster/afford. Therefore, what happens at one end of a transmission line DIRECTLY affects the other, and vice versa. And so, properly applying an adjustable LC impedance matching network in the shack CAN (and often does) modify the resonant frequency of an antenna. 73 de John, KD2BD ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
