Al,
It is somewhat unconventional to all of us used to single wire antennas.
That is why it works better than the Isotron, the EH, or the other small
antenna ideas that do not contain full resonant lengths of conductors.
Steve chose to build his first prototype in the photo for 20m, as I
understand it. The same size cone can be used for 20m or 10m, just the
parallel folded line(s) you construct has to be greater than a half dipole
quarter wave for the band of choice. But for a given length of parallel
line, you get one band. The bandwidth between 3:1 SWR points is very flat
and is a good 10 per cent of the frequency, quite good among small antennas.
The ten meter model uses four of these folded monopoles spirally around the
cone. This photo shows a ONE folded monopole for ease of understanding.
Four gets you above 90 per cent efficiency. One can be as good as 60 per
cent.
A small loop (MFJ) may be only 10 per cent efficient. But with good
propagation, 10 per cent can work a lot of the world, and 60 per cent a lot
more,and 90 plus per cent is just below the old dipole at 94 plus per cent
or so, give or take for its construction.
73,
Stuart K5KVH
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