> Where does the 2 dB come from?
>
> It comes from a mistake.
>
> A couple of fellows measured some quads on 440 MHz and
> assumed the measurements were accurate. That data made it into
> books. Unfortunately they overlooked some errors, and the results
> were flawed. But to this day people still quote the flawed
> conclusions, 2 dB gain over a yagi the same boom length.
>
> Now you see why I pick at measurements and insist they include
> and describe potential errors (and there are ALWAYS potential
> errors). Once something is in print, it remains almost forever even
if
> wrong.
>
> 73, Tom W8JI
> w8ji@contesting.com
I'm convinced the wrong Quad gain issue got enforced by a number of
rough comparison between 2/3 element tribanders yagi and tribanders
quad, expecially if performed on 20m.
Since most manufacturers claimed for years unreal gain figures for
their tribanders, as usual indicating a maximum theoretical gain (but
still claiming F/B), it's obvious that any comparison with quads (i.e
HiGain TH2/TH3 vs Hy Quad) couldn't show anything else than advantages
for quads, possibly more than 2 dB.
Incidentally, loaded elements in a tribander yagi noticeably decrease
its real gain, and a two element monobander (yagi) would exibit nearly
the same advantages of the quad over a typical 2/3 elements tribander
on a short boom.
The feature where a two element quad outperforms a two element yagi
(keeping the gain comparable) is F/B.
73,
Mauri I4JMY
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