Hi Frank,
> I sort of understand why. Vertical antennas may be the only
> reasonable DX radiator for topband. Actually, verticals are
> probably a good alternative to beams on the higher frequency
> bands. The only problem is the radial thing.
Verticals also have more Fresnel zone losses, because the area
where pattern is being formed involves a large area of the earth and
things on the earth around the antenna. That isn't as much of a
problem on topband, but it is a major issue above 40 meters.
> I know that the GAP antenna is a linear loaded, vertically
> polarized dipole. No radials required. Why isn't there
> more traffic on it being used as a solution?
Because it (like many "no-radial" or "few-radial" vertical antennas)
has horrible efficiency, for a number of reasons.
> understand why a linear loaded solution to make the
> mechanical problem go away has not received much interest.
Linear loading is no more efficient than a lumped component. As a
matter of fact all things equal (loading device wire size and effective
loading location) it is less efficient than a lumped component.
The only way to decouple a vertical from the lossy earth below the
antenna is to move it 1/4 wl or higher above earth or to lay down a
mess of radials. There is no other solution. It would be nice if there
was.
Many people live quite well with a less-than-ideal antenna, and
make lots of contacts. Do the best you can.
>73, Tom W8JI
w8ji@contesting.com
--
FAQ on WWW: http://www.contesting.com/FAQ/topband
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|