[Elecraft] Home made Sigma-GT5 & KRC2 or SGC?

[Vic Rosenthal]

Earl W Cunningham wrote:

> It has since been proven (by field strength measurements far from the
> antenna and by modeling using NEC4) that elevated radials less than 0.5
> wavelengths above ground are only slightly better than the same number of
> on-ground or buried radials.  Therefore it is advisable that if you use
> elevated radials, then use a lot of them, just as you would do if they
> were on the ground.

I don't think I would say "only slightly better".  My experience has 
been, for example, that a 160-meter inverted L with two on-ground 
radials barely works, while one with two tuned radials up about 10 feet 
works OK (not great, but OK).  I would like to read the reference on 
this and would appreciate it if you would point me to it.

> On the other hand, it has been shown that shortened elevated radials
> resonated with a loading coil has only a small effect on the efficiency
> of the radials as compared to long elevated radials.
> 
> Rather than a separate coil in each radial, some have reported good
> success by tying all of the short radials together and loading them to
> resonance as a unit with only one coil.  The apparent reason that this
> method is chosen by many is that is is very difficult to individually
> tune every radial exactly alike and only one or two of the radials will
> "hog" the ground return currents.

And the result of this hogging is a serious distortion of the pattern 
that gives rise to very high-angle radiation, which is useless for all 
but the most local QSOs.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco