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From: "Richard Date: Wednesday, November 26, 2008 12:00 PM Roy and others have answered this one in the past too. You employ the near field table to observe the ground wave. It works approximately well, even out to the edge of the implicit flat universe. If you object to flat universes, you are no longer in the realm of ground wave. If anything, modelers give MORE response in comparison to the BL&T data. Then I posted my result of using the near-field analysis of EZNEC showing a value much LESS than the "modeler" value for those conditions when using the BL&E data and the FCC curves. Following that is posted: From: "Richard Clark" Date: Wednesday, November 26, 2008 3:32 PM I modeled their structures as they built them explicitly (they had many variations), at the frequency they used, took readings at the distance they reported. For your 1 kilometer distance (not one they used), I get 303 mV/m at 3 MHz for their 70 foot radiator over a field of 113 x 135 foot radials with an average ground conductivity. When I use their distance of a mile, I get 188 mV/m, all else identical. Their paper reports by formula that I should see 194.5 mV/m. ... No, the BL&E paper (accurately) stated that 194.5 mV/m is the theoretical maximum field possible at 1 mile for 1 kW radiated by a perfect 1/4-wave monopole over a perfect ground plane. The peak values they measured came very close, but never quite achieved that value. It would appear that with the average of the two distances, my model accords quite closely to BL&E. Mr. Clark - kindly note that in your first quote above you say that, if anything, "modelers" show MORE response than BL&E Then when pressed a bit you say that your model "accords quite closely" with BL&E. Yet the results of my EZNEC near-field model showed considerably LESS ground wave field at 1 km than either the FCC approach or the BL&E data. Clarifications, please? RF |
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