On 10/31/20 4:11 PM, jimlux wrote:
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
Curse spellcheck - Owens Valley
the Owens Valley Radio Observatory (OVRO) is located near Big Pine
(between Bishop and Independence)..
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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