[TowerTalk] Breakall short vertical
Terry Conboy
n6ry at arrl.net
Fri Jun 11 15:12:36 EDT 2004
Kintronic also has a link to a more theoretical IEEE article on this antenna:
http://www.star-h.com/publications/ieee2002.pdf
In the end, this is just a permutation of a short fat vertical with a large
capacity hat. For short verticals, these work pretty well, but as Tom
mentions, the ground currents are still relatively high, since the 4 wires
all dump equal, in-phase currents into a common ground system. If you have
120 radials, the ground losses are quite small and the efficiency is
good. If you have a more typical sparse ham ground system, the losses can
be noticeable.
I was surprised that the authors (PhDs, MSEEs, and PEs notwithstanding) of
these papers don't seem to understand the realities of the ground
currents. One of them also conspired to write another paper on folded
unipoles that propagates the same mischief.
http://www.dlr.com/dlrweb/papers/nabpaper/Nabpaper.htm
Terry
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