On Thu, 08 Mar 2012 12:35:58 -0600, NM5K wrote:

On 3/8/2012 11:09 AM, dave wrote:
On Thu, 08 Mar 2012 08:51:20 -0600, NM5K wrote:

Also, ground mounted verticals will still need radials if the antenna
is to live up to it's expectations. And there is nothing to stop one
from using one elevated, if one uses resonant radials for each band to
be used.

My GAP Titan DX requires no radials; it is a center fed, asymmetric
vertical dipole.


Well, ground mounted monopoles in his case.. Being a "complete" antenna,
it's true that the center fed vertical does not require radials for
proper operation, but you would still likely show lower ground losses if
it were over radials. For instance, broadcast stations that use 1/2 wave
radiators still use a set of radials under the antenna. Usually 1/2 wave
radials, when used with a 1/2 wave radiator.
You will still see some ground loss with the ground mounted 1/2 waves
over poor ground, but being as the max current point is 1/4 up from the
ground, it's not near as severe as the ground mounted 1/4 wave where
maximum current is at the base.

I don't think a ground screen is needed if you are 1/2 wave.

If you elevate a short vertical you only need a few "ground" radials
(think CB groundplane antenna), btw. My whole transmit antenna system
floats on my roof. The only "ground" is the panel where the RF goes
through the wall. I receive on a balanced 30m horizontal loop, also
floating except for the point of entry. I have an automatic tuner at the
feedpoint under the eave by my kitchen window. (FWIW) I have lived here
14 years and have never seen lightning at the shack.