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Re: [TowerTalk] Cover antennas - the good news and the bad news

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Cover antennas - the good news and the bad news
From: jimlux <jimlux@earthlink.net>
Date: Sat, 31 Oct 2020 16:11:47 -0700
List-post: <mailto:towertalk@contesting.com>
On 10/31/20 2:19 PM, Michael Tope wrote:
It would interesting to take a known good antenna like a monoband Yagi (or perhaps a SteppIR) and do a set of measurements over the course of several days to evaluate the measurement repeatability. If someone had designs on doing a K7LXC/N0AX type antenna evaluation study, this would help determine the size of the error bars for measurements of different antennas taken over the course of several days. Stable weather would likely be a desirable characteristic of the measurement environment (no drastic changes in ground characteristics during the measurement period).

excellent point..



I had to use Google to get the bagpipe joke :-)



Here's some actual measured data from a site in the Owen's Valley

http://jim-lux.blogspot.com/2020/10/permittivity-under-antennas-there-is.html

There were significant variations in the surface soil properties (4" deep), but since skin depth for HF is substantially more, it's probably stable over a day or two, assuming it doesn't rain or it's continuously raining.

But substantial changes over months, so if you've got a vertical, that's going to make a difference.
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