2020-04-30, 15:49:57
(2020-04-30, 13:48:25)Rob_Walker Wrote: John, does a loop perform better the higher up it is?If any antenna is close to ground some signal is lost but, in some cases, other factors are improved. I have experimented with "Grasswire" antennas which are actually laid directly on the ground, with surprising results (read: http://f5ad.free.fr/Liens_coupes_ANT/G/K...0gazon.htm).
The general rule is to get an antenna up high; ideally a half wavelength above ground. However, that's impractical for the low bands like 80 meters. If a loop is at least 30ft up it will perform well on all bands.
There is a mode called NVIS (Near Vertical Incidence Skywave) that relies on an antenna being low. The propagation is almost straight up and, below the critical frequency (foF2), the signal will be reflected by the F2 layer in the ionosphere over an area up to about 400km from the transmitting station. Currently at our latitude NVIS only works on the 80m band by day and the 160m band at night.
GBARC has an 80m SSB net every Wednesday evening. I hope you'll join us when you're ready. Most of us communicate by ground wave on that net so antenna height isn't an issue.
Hope that helps Rob.