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Joel Koltner wrote:
Hi Tim, "Tim Shoppa" wrote in message ... On Mar 22, 9:24 pm, "Joel Koltner" wrote: I think his method, especially for physically compact antennas and feed systems which tend to have very low radiation resistance at HF frequencies, is a great check on theoretical calculations. There has to be a meeting point between mathematical models/NEC and reality and he is working at one such point. Agreed -- the controversy comes into play in that he ends up computing electrically-small loop antennas as being upwards of 70-90% efficient, when everyone "knows" that such antennas are typically 10% efficient. He even goes after Chu/Wheeler/McLean/etc. in suggesting that the fundamental limits for the Q of an ESA are orders of magnitude off (slide 47), and that's pretty sacrosanct terriority (see, e.g., www.slyusar.kiev.ua/Slyusar_077.pdf -- even the Ruskies buy into the traditional results :-) ). One wants to be careful about "Q" and Chu, etc. If you haven't actually read the paper, you might think that Chu is talking about Q as in filter bandwidth (e.g. center frequency/3dB bandwidth), but it's not. It's the ratio of energy stored in the system to that radiated/lost. For some systems, the two are the same, but not for all. |
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