"That is a pretty poor SWR curve for a 4 element Yagi."
It is important to remember that SWR is NOT a measure of antenna
performnance, it is a measure of the match to the transmission line.
Values below about 2:1 matter ONLY to the extent that the power amp can
drive them efficiently to rated power. Some amps have wider tuning
ranges than others.
Worst case excess loss due to that SWR is only a few tenths of a dB, and
that would be for a pretty long line.
The FAR more important parameters are horizontal and vertical patterns
and gain that are uniform over the needed bandwidth.
Also, the better designers of Yagis like N6BT and G0KSC try to optimize
their designs so that their operating parameters are less sensitive to
mounting height. Any antenna, of course, will have its vertical pattern
influenced by ground reflections in the far field.
73, Jim K9YC
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