[TowerTalk] Adjusting a Gamma Match on a Yagi with an Antenna Analyzer

Chuck w5pr at swbell.net
Mon Nov 8 18:49:06 PST 2010


I hate adjusting gamma matches through trial and error.  I am hoping my new antenna analyzer will help.

I computer designed a 10 meter Yagi which designed at a feed impedance of 31.2 + j18.3.  This is inductive, I assume.

I have a gamma match, the antenna mounted at 15 feet and my antenna analyzer says (through an analyzer measured 1 wavelength 50 ohm feed line) Z=66 ohms, X=-52 ohms and C=105

My take is to move the tap closer to the boom until it is about Z=50 ohms and, if there is still a negative X, to lengthen the DE.  Of course, the changes will interact with each other and I will need to go back and forth until Z=50 and X=0.

Am I on the right track?

Chuck W5PR


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