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Does paint affect a Yagi?

Jan 17th 2013, 02:40

KO0Y

Joined: Apr 7th 2012, 19:22
Total Topics: 0
Total Posts: 0
I put up a small Cushcraft Yagi, and it does what I wanted. I'd like to spray paint it with a Rustoleum green to make it less conspicuous among the trees. Would that affect its performance? I would not paint at the feed point, of course, just the mount and elements.
Jan 17th 2013, 14:09

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

I modeled a 10M dipole to see what effect a typical layer of paint would have--it moved the resonant frequency by just 10kHz, a negligible amount. EZNEC will let you model a dielectric coating on your wires.

http://ipnpr.jpl.nasa.gov/progress_report/42-138/138F.pdf
It is hard to get good measurement data at HF, so looked at the microwave data and decided that a dielectric constant of 10 would be a very, very conservative guess. The paint thickness is typically around 1 mil, according to some web searches. It is a good idea to paint the feed point to protect it from the elements.

Zack Lau W1VT
ARRL Senior Lab Engineer
Jan 17th 2013, 15:10

KO0Y

Joined: Apr 7th 2012, 19:22
Total Topics: 0
Total Posts: 0
Thanks; I did not know EZNEC would do that. I've covered the feed point with that sticky coax seal, and we live in a dry climate, so that should be OK. I should have mentioned that the antenna is a 3 element 2 meter Yagi.
Jan 25th 2013, 22:26

KF5VPK

Joined: Jan 16th 2013, 01:39
Total Topics: 0
Total Posts: 0
Asking your local paint store would help to. I know some paints couldn't be used on antennas when I was in the US Navy years ago. They would block transmissions.

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