N0AH wrote:
> Today, all test were at the feedpoint, without the UnUnm
> including trying two different short feedlines of a few feet-
> They both showed the same- the minimum SWR is finally creeping
> up a bit, from 1:1 yesterday to 2.1:1 today- then it rained
> again- I feel the ground soaked earth is causing some
> interesting measurements on the antenna. Very unexpected. In a
> few days, once we return to a scortched earth, it will be
> interesting to see what happens. If the SWR goes back up to 5:1
> or so without the UnUn in line as things dry out, that is, just
> measured at the feed point, this would be an interesting topic
> to discuss- If it remains low, then I'll just look at the
> loading coil - but since it rose up some today, I really feel
> the drying out saturated ground is messing with things- thx for
> all the awesome responses- This is a good topband antenna for
> small back yards from our view-
I think you are seeing improvement in ground plane conductivity situation and
it's effect on antenna.
One half of the vertical is in the radials/ground.
Using fewer and shorter radials handicaps the overall performance.
Watering the ground in vicinity of antenna/radials makes that other half less
lossy, improves performance. Add some salt and you got even mo' RF.
Antenna system should be seen as ANTENNA in the ENVIRONMENT for the overall
performance. Ground/soil is that RF mirror that affects the performance of
antenna, forming the beam pattern - angles and magnitude.
Ocean front adds 10 - 15 dB. One or two elevated radials on the beach will beat
60 radials on dry ground, adding Fresnell zone for added efficiency and lower
angle.
This is approximated by the rain soaked neighborhood, modulated by the soil
conductivity.
I used to fertilize and water the heck out of my backyard under the Big Bertha
and Razors before the contest. No scientwific data, but felt good and scores
were fixing some records.
73 Yuri
see you all at Tesla Radiofest BBQ this Saturday July 23
www.TeslaRadio.org
www.MVmanor.com
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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