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Yuri I sure disagree about being able to determine an antenna's efficiency by either resistance measurements or by measuring received signa;l strength at any one point in space. But, you are certainly a much smarter fuy than I ever was. So, I am not equipped to get into a news group contest. It is my contention that the antenna under test's complete radiation pattern and field strength would have to be measured and integrated if field strength is used to determine it's efficiency. That could get coplicated. It would have seemed to me that the loss in any "R" is dependent on the current flowing in it. And, I'd be concerned that any resonances could have higher circulating currents at the operating frequency. If you can point out the errors in my convictions, I'd like to read about where I'm wrong. Jerry "Yuri Blanarovich" wrote in message ... But, if the "wonder antenna" is small enough to be enclosed (mostly) in something transparent to the RF but not to the thermal thats generated by any I^2* R losses, wouldnt the temperture rise inside the enclosure give a decent indication of efficiency? No need for that really, too cumbersome. If you measure R you can calculate losses due to dissipation in heat. Again, real comparison of efficiency of shortened antenna is to compare against the same pattern producing full (electrical) length antenna, everything is included in what you would measure. Much simpler too. I can build quarter wave vertical faster than styrofoam igloo. :-) Basic rules are, best inductive loading is about 2/3 up the radiator, coil is better than loading stub, top hat is the best. Anything else is jocker's attempt at perpetuum mobile. Yuri |
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