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In message , Jeff writes
Anyway all of the article can be blown out of the water by some practice measurement of a real life situation, which will show that a 3:1 mismatch will produce the same loss regardless of whether it is Zo*3 or Z0/3 when you are talking about feeding an antenna. Jeff Great, Jeff! I would support your suggestion to make measurements. All you need to do is set up his scenario and collect some data. Please use his identical set-up to confirm or refute his results. If you have understood what I have been saying at all then you would understand that I am not refuting his results (at least to a first approximation). What I am refuting is the extension of his results to the 'normal' case of feeding an antenna, which he tries to do in the later parts of the article. In reality you do not need to do the experiments, they have been done many times, and the loss in a feeder under mismatch conditions is well know and documented. It is these results that the author is challenging from the wrong standpoint of a short line which is not extensible to other cases. My understanding is that when there is a standing wave on a feeder, the additional SWR loss occurs because the higher 'I-squared R' losses at the current maxima outweigh the lower 'I-squared R' losses at the current minima. If the feeder is not long enough to have a current maximum (or anything like it), and the load mismatch is higher than Zo, the typical current on the feeder can be lower than it would be if it was correctly terminated. If so, the feeder loss can actually be lower than would be if it was correctly terminated. As I confused? -- Ian |
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