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:
Gain per unit length of boom
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October 22nd 04, 01:16 AM
Tom Ring
Posts: n/a
wrote:
My ARRL books go back a decade or more
and the graph showing gain per boom length
has several curves based on different measurements
e.t.c. Has a graph been made based solely on NEC
program findings over say a perfect ground and at a uniform height?
Art
For VHF/UHF yagis in free space -
WA2PHW Gain Figure of Merit
G = 10 log (5.4075 B + 4.25) for B GT 1
Where G is gain in dBd and B is boomlength in wavelengths.
This is from a database of over 100 VHF/UHF yagis compiled in the early
90's. These are all real buildable yagis, and the antenna range numbers
closely agree with the computer models. The numbers were heavily
influenced by the 10 to 40 element K1FO series. Thanks again Steve.
Note that this predicts a zero length yagi should have about 6 dBd gain.
Any ideas on why it intercepts there?
tom
K0TAR
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