Hi Tom, I NEVER claimed the folded conical Helix was better than all other
antennas, I said it was more efficient than some small antennas of
comparable volume which it is. The Isotron and most other small ham antenna
designers for example, have NEVER published Wheeler Cap Efficiency
Measurements, nor have I seen those on the EH web site. I have not seen a
16 inch loop for 10m measured by the Wheeler Cap, but think that would be
instructive for us to do.
I have received other emails confirming that some small loops are only 10
per cent efficient. By definition of Wheeler, Bob Rogers is concentrating
on antennas in the kr range of 0.1 to 0.01 ONLY at this time. As we all
know, how you build a small vertical loop is all important in its
efficiency, and to tune it you have to have a lossy component, and
minimizing that loss is the major part of the loop battle. Small loops can
be made to work, but certainly do not have a 10 per cent bandwidth at
several bands as does the Folded Conical Helix.
The Cone appears optimum at this time, for getting a resonant length of
folded element into THIS volume, without excessive blockage of radiation
from one element and neighboring elements, and having something with low
angle radiation, vertically polarized.
With all due respect,
Stuart K5KVH
|