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.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|