"Hal Rosser" wrote

You might be mixing dc-theory with rf, and looking for a particular
relationship that's not there. The antenna is not 100' higher
electrically
as you suggest. In terms of your 100' ground rod, just because it might
take
that deep a hole to achieve say, 5 ohms dc-resistance, that does not
make
the surface or an antenna above it at an elevated potential with respect
to
each other.

A dipole certainly behaves differently over varying resistances of
soils.
But the efficiency differences have never been equivalent to the antenna
being at a different elevation because of soil conditions. Now maybe I
get
away with less ground loss from a half-wave dipole that is not quite a
half-wave above ground, because my soil is very sandy, is that what you
meant? It doesn't change the electrical height of my antenna any, but
the
soil is such a lousy conductor that less is absorbed by a slightly
too-low
antenna.

Jack

You're probably right - but then why does the operator on the hill get
better recption than the one in the valley.
if sand is an insulator, then being on top of a 100-ft pile of sand would
be
like at the topp of a glass tower, right?
why not?


Well, the irony of which Fred (W4IJE) replied surely applies - it seems to
have the same effect as "raising the antenna", which I did also admit. So
the only point I struggled to make was it is not electrically higher. Height
of an antenna surely helps us in all cases, and part of that is related to a
dipoles most efficient design height above ground, part is because we clear
interfering objects in the near and far fields when we "elevate" ;-)

I wouldn't stand on a tall sand hill in a thunderstorm, lightning would sure
be happy to race through you and down the side of the sand pile on its way
to a more conductive earthing! But a dipole erected 1/4 - 1/2 wave above the
same tall sand pile should be quite happy - especially if the Atlantic Ocean
was on one side, the Chesapeake Bay on another, and inland waters on a third
side. That pretty much describes the "hill" off the beach that I live on.

73,

Jack
Virginia Beach