Topband: Elevated Radials

[Jim Brown]

On 1/5/2024 11:32 AM, Frank W3LPL wrote:
> Unless you live on a salt march (there aren't many in Ohio 😉,
> horizontally polarized antennas are significantly more efficient than
> verticals on every band except 160 meters, even if 80 meter horizontally
> polarized  antennas ore only 70 feet high and 40 meter antennas are
> only about 50 feet high.

YES! This is entirely consistent with an extensive modeling study I 
published about ten years ago on how horizontal and vertical antennas 
interact with ground. In essence, horizontal antennas care greatly about 
height but hardly at all about ground quality, while verticals are VERY 
strongly dependent on ground quality in both the near and far field.

The study allowed me to develop a Figure of Merit in dB for the height 
of horizontally polarized antennas on 80 and 40M. The study also showed 
that a quarter-wave is the optimum height for NVIS, and that only a few 
dB is lost up to a half-wave.

The study also showed that the typical multi-band HF vertical benefits 
from mounting at typical roof-top heights, provided that those that are 
essentially loaded/trapped quarter wave designs have at least a couple 
of radials per band. Two reasons for the benefit -- first, reduced 
ground losses, second a better vertical pattern.

The write-up I published of the study is here.

http://k9yc.com/AntennaPlanning.pdf

NCJ wanted to publish it, but HQ publishing couldn't deal with the 
graphs. It was peer-reviewed by sharp engineers when I presented it at 
an NCCC meeting. Vertical vs horizontal is quite consistent with my 
on-the-air experience. For a couple of years, I had a 160 dipole at 
about 120 ft in addition to a 100 ft Tee vertical with a lot of radials, 
and did a lot of comparisons. The dipole rarely beat the vertical. 
Another observation -- during the daylight hours of 160M contests, I can 
reliably work good stations up to about 800 miles with the Tee; with the 
dipole, never even a QRZ?  The logic is simple -- even at 120 ft, it's a 
low dipole on 160M. :)

73, Jim K9YC