Topband: Tuning elevated radials

[Tom Rauch]

<<So what's the fix?  It seems to me that the area
underneath this vertical needs to be beefed up.  Even though
the tower insulators are about 10 degrees above the earth,
should I consider attaching the tower legs to the elevated
radials?  Then, beef up the base with a radial system the
best I can?>>

If you use an elevated counterpoise with only a few radials
(say less than half-dozen radials) you can give up about a
dB just by having the elevated system tied to earth through
the coax shield path.

  I know I cannot run full 1/4 wave length radials in
uniformity around the compass, but I bet I can slip quite a
few 50' to 70' radials into the sod and attach them to the
lightning ground rods at the base.>>

If you have your elevated radials connected to the ground
rods somehow odds are good the connection decreased
efficiency slightly.

30 or 40   50-70 foot radials are probably acceptable. You'd
have a good lightning ground with those radials. They would
help your other antennas to some extent, and that system
would work on any HF band. The antenna itself will be
broader in BW than with elevated radials, and all the "my
radials radiate" problems would vanish.

<<radials."  Going from 4 to 32 -- 20M long radials on 80M
provides only 0.75dBi of additional gain.  Figure 9-14 is
average ground and supposes an additional 1.75 dBi of gain
when going from 4 to 32 radials.>>

I don't know what the source of that data is. I can tell you
this, every time I've seen four radial systems on measured
by FS meter, FS increased about 3-6dB going from four to 50
or 60 radials. If the radials are up in the air you can use
less. FS measurements published in an engineering article by
a fellow from Brazil showed 8 radials 1/4 wl above ground
were just a fraction of a dB weaker than the FS produced by
a vertical with 120 buried radials. Of course 120 radials
and 50-60 radials are about the same.

 On a band whose MDS is noise limited anyway, from a gain
standpoint, who cares?>>

You will on transmit. When a signal is close to noise floor
even one dB change sounds major.

73 Tom