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#18
February 16th 08, 06:25 PM
posted to rec.radio.amateur.antenna
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Vertical Antenna Performance Question
AI4QJ wrote:
"Richard Clark" wrote in message ... On Fri, 15 Feb 2008 12:37:55 -0800 (PST), wrote: AI4QJwrote: I suspect that the EZNEC program is not designed for taking into account such "rare" phenomena as "ground wave propagation". So much for EZNEC analysis at 75m. ... EZNEC information tells you nothing about ground wave propagation. Two things wrong with this: 1. EZNEC does provide information about the radiation characteristics along ground at any distance on an infinite, flat plane and at any elevation above it; Really? Can it follow the curvature of the earth from say, Illinois to Germany? Is there some part of "infinite, flat plane" that you fail to understand? 2. EZNEC is not a propagation modeler as its users are well aware; If it cannot predict take-off angle then what good is it? It doesn't matter if we warm the clouds directly above? EZNEC provides horizontal, vertical and 3D radiation patterns. Is there some other dimension you are interested in? 3. EZNEC models the 100M work of Brown, Lewis, & Epstein quite closely. There is nothing in the body of RF literature to suggest that the nature of radiation shifts suddenly in 7/8ths of a megahertz. Yes, there is no abrupt shift at 75m (most obviously). Quite simply, as you approach larger wavelengths, skywave characterstics lessen and groundwave characteristics increase. Which are functions of propagation, not antenna modeling. But I am a heretic for not having mindlessly bowed in adoration at the altar of the EZNEC god in blind faith as you and others have done. However, those fanatic evangelists who live by blind faith alone have wisely plonked me so as not to let their blood pressures rise at the spectre of the EZNEC god being angered. No, you sound more like someone with a grudge mixing apples and oranges. -- Jim Pennino Remove .spam.sux to reply. |
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