[TowerTalk] M2 40 meter Yagi

[Jim Brown]

>> "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