Joseph, I dug out an old Army Signal Corp training manual TM 666-608 and
on page 128 they have a section on top loading. Figure 117 on page 129 (TM
666-121) recommends that the flat top consist of a 1/4 wave wire folded
back on itself and fed with the down lead on on side. This would make the
flat top 1/8 wave long on 1.8 Mhz, a very manageable length for most. I
used to have frequent contacts back in the Stew Perry days with G stations
running no more then 10 watts to this arrangement. The merely referred to
their antennas as "Marconi's in the garden", nothing more. It makes sense
that the folded 1/4 wave would cancel radiation while still forcing, I
would presume, the current loop at the top of the down lead. Such an
antenna, made out of twin lead was used by me for years on dxpeditions. ( I
would throw the twin lead portion over a palm tree on the beach!) It was
this antenna that allowed me while traveling abroad to provide W1BB in the
60's with the remaining new countries for the first ever 1.8 DXCC. The
Signal Corp version uses open wire spreaders which would be a must if there
was any power involved.
Herb
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