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In rec.radio.amateur.antenna gareth wrote:
If short antennae radiate all the power that is fed to them, then why would anyone use long antennae, because the first part of such an antenna, the short part, would radiate all the power, and then there'd be nothing left for the extra bit, making up the rest of the long antenna, to do? An antenna radiates as a whole, not as parts. The answer is, of course, because it is more difficult to feed a short antenna because of its reactance. Nope, the reactance is fairly easily canceled. The answer is because the radiation resistance is measured in milliohms and a matching network to match 50 Ohms to milliohms has huge resistive losses. So, whence does this reactance arise? As your base assumtion is nonsense, this is rather irrelevant. Simple. It is the power that has NOT been all radiated by the short antenna arriving back at the feed point with an awkward phase relationship with the incident power. What happens to that power that has not ALL been radiated when it arrives back at the feed point? Simple. It passes back into the matching network, which, together with the short bit, form the resonant artefact, where much of it disappears as heat in the matching network before being fed back to the short antenna to start all over again. Now, Stephen Thomas Cole, that well-respected font of all technical knowledge over in uk.radio.amateur is saying that all you Yanks are a bunch of dopes if you do not understand the above, so take it up with him over there. Babbling nonsense based on yet another false assumption. -- Jim Pennino |
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