>>If you do an NEC model with a second reference vertical, say 5
>>wavelengths away, and look at the amount of vertical power received by
>>the second reference vertical, then you will see that the horizontal
>>section of the inverted L contributes nothing, whereas a T top actually
>>increases received signal.
5 wavelengths away is hardly in the far field, with some degree of common
ground between. Even at a mile, one is still talking about ground wave, and
to draw small distinctions, one needs a model that DOES groundwave, and
DIRT, WELL. Only the pro grade modeling programs do dirt even halfway
decently. As some others here would say, model to get on the right planet,
then cut and measure, then talk to me.
Two other things work against what you propose. 1) Hams use skywave. 2)
Horizontal wire and horizontally polarized radiation are two different
things.
A horizontal end to the quarter wave only puts out purely horizontal
polarization broadside to the horizontal. Off the ends to sky wave angles
it ADDS to the vertical polarization, an effect that would hardly be seen
with 5 wavelength separated like antennas. "Increasing received signal" is a
quite fuzzy statement that needs to be carefully qualified in order to map a
model to it. Even then in real life the vagaries of real dirt in the quarter
mile radius around the vertical, and the radial system itself will swamp
many times over any theoretical differences between one or two 1/8
wavelength "tails" at the top of the vertical seen from many miles via
skywave.
I would suggest that the "hang-ability" and maintainability of an antenna in
an L or T configuration at a given ham's site far outweighs any theoretical
difference suggested by the models. And overall for performance, it's still
radials, radials and radials.
73, Guy.
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