Being pedantic sorry.. A better word to use is negligible.

I work on microwave transmitters and even solder flux can have an effect
on the output power. Small but measurable.

I suspect that if you really caked it on silicone spray might be RF
absorbtive. I'll admit that I havent checked though!

You can also heat the dish periodically. The issue I guess is how much
it affects the received signal and whether one has enough S/N margin to
just ignore it.

Cheers Bob

wrote:

silicone spray has no effect on signal strength at all