To: | "Dan Zimmerman N3OX" <n3ox@n3ox.net> |
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Subject: | Re: Topband: Ground conductivity, permittivity measurement |
From: | "Tom W8JI" <w8ji@w8ji.com> |
Reply-to: | Tom W8JI <w8ji@w8ji.com> |
Date: | Tue, 2 Oct 2012 14:30:18 -0400 |
List-post: | <topband@contesting.com">mailto:topband@contesting.com> |
I don't know about further out where you'd have to proof an AM station but I just ran some models and there's kind of a weird relationship between vertical electric field strength at 1 wavelength out and far field efficiency as ground conductivity is varied for fixed permittivity. One wavelength is too close to show ground loss changes. You are really just looking at radiator efficiency. The signal has to propagate for some distance on groundwave to show earth conductivity effects on signal level. What I was suggesting is if soil varies from rain as much as a ground rod test shows, we should see this change at a distance on groundwave. BC stations determine soil conductivity by the measured slope of attenuation with distance compared to an ideal attenuation slope. I was wondering if ground rods were ever correlated to a known way of determining soil conductivity. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK |
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