Mac, PY2CW wrote:
"My question is: What is better for top, with non ideal
ground/counterpoise (i normally park the motor home in good soil, and
deploy 4 + quarter wave roof height radials).
1) 30 ft vertical linear loaded whip (typically awg 18)
2) 30 ft vertical whip / silver plated - big loading coil at base
3) 30 ft whip / base and center loading
4) 30 ft vertical / 30~60 ft horiz wire / linear or base or center
loading ( Inv L )"
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Option number 4 above (inverted L) would be the best antenna. If you
cannot make the horizontal section long enough for a full 1/4 wave, put
the loading inductance as far from the feedpoint of the antenna as
practical.
Although the radiation efficiency of any vertical antenna depends mainly
on the extent of the ground radial system, I would rate how a topband
antenna (within your constraints) gets out for DX as follows:
1) Inverted L with loading coil in the horizontal section.
2) Inverted L with loading coil at the top of the 30-foot vertical
section.
3) Linear-loaded 30-foot vertical.
4) 30-foot whip center-loaded with coil.
5) Base loading, regardless of the conductivity of the antenna conductor,
is the least desireable method of loading a vertical antenna from an
efficiency standpoint.
73, de Earl, K6SE
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