[TowerTalk] Dayton Antenna Forum (contd.)

[Pete Smith]

Someone asked about presentations at the forum, and thus far there has been
no reference in replies to ON4UN's talk,  Following is solely my
recollection and interpretation, so don't blame John if it's incorrect.

The basic focus of the talk was to refute articles and past forum
presentations arguing that at HF, a small number of elevated radials at a
relatively short distance above ground can produce as good field strength
as an extensive radial network on or under the ground.  John pointed
approvingly to W8JI's experimental work which found a few elevated radials
to be as much as 5 dB inferior to a full ground plane.  He said that the
previous papers had ignored inherent inaccuracies in modeling software
which produce exaggerated gain figures for wires close to ground.  He added
that in his view, the last few years had been a "golden age" for writing
articles using modeling rather than experimental results, and that this
instance demonstrated the pitfalls of doing so.

ON4UN noted that there are a couple of circumstances where a few elevated
radials can work well -- in particular, over or near salt water and over an
area where an excellent ground screen already exists.  For example, he
referenced the 6Y2A operation's use of verticals on the beach, and his own
use of single elevated radials for his 80m 4-square, which is placed over
the excellent radial field of his 160-meter antenna.  After the
presentation, I had a chance to ask him why he had bothered with the
elevated radials when he had an excellent ground screen to work against,
and he replied that he had done so to elevate the bases of the verticals
above the roof of his house, thereby placing the high-current part of each
radiator more in the clear.  He said that this could be an important
consideration.



73, Pete Smith N4ZR
n4zr@contesting.com 



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