REFLECTOR: Antenna Degradation Due to Metallic Paint on Bottom

Dave Black dvblack at comcast.net
Mon Jun 6 13:33:35 CDT 2005


Richard,

> >Has anyone experienced significant (embedded) antenna performance due to the
> >use of metallic paint on the bottom of their aircraft?
> 
> I did a bunch of experiments with metalic paint (and primer containing Zinc
> and Zinc Chromate) covering a GPS antenna.  No degredation at that
> frequency range at least.

It seems to be "common knowledge" that metallic paint will degrade antenna
performance. But I really can't see why it should. The metal particles in the
paint are way too tiny to have significant impact at the (much longer)
wavelengths involved. Generally speaking, metal bits smaller than 1/8
wavelength should be virtually invisible to an antenna. Unless the bits are
electrically tied together. 
 
> Carbon fiber, OTOH, cut it off completely.  Which makes me think it could
> work as a ground plane.

I concur here as well. From the perspective of radio waves, carbon fiber
behaves the same as aluminum. Both are electrically conductive, and opaque to
radio waves. I've never heard of an antenna or ground plane made of carbon
fiber, but am certain they would work virtually as well as their
aluminum/copper counterparts. 


Dave Black
Shortwing RG


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