There are hundreds of variations of carbon fiber "mixes". Some have
absolutely no effect on internal antennas, and some that are absolutely
wonderful Faraday shields (blocks) of radiation performance. My work with
Rutan on Voyager pretty much proved that.

HOWEVER, having said that, we proved in the Bellanca experiments that
regular old silver UV dope on fiber has absolutely no effect on internal
antennas. Even the FAA accepted our experiments on that.

On the other hand, mixing carbon black, which is not a conductor, nor an
insulator, but a lossy medium is in fact an antenna attenuator. For some
manufacturer of kits to come out and say, "hey, we started putting in carbon
black to our mix and now we've got internal antenna problems" isn't a great
surprise.

I work real cheap. I'm not a thousand dollar an hour consultant. You'da
thought that all you who are spending tens of thousands of dollars a kit
would have had professional antenna consulting from these yahoos who are all
of a sudden discovering that moving this or changing that is having an
effect on their antenna performance would come to the source for advice.
Not a one of them, other than Bellanca and Beech. Cheap *******s.

To the person that asked whether carbon black has an influence with internal
antennas, I pose the following question:

We proved at Bellanca that reflection from aluminum particle to aluminum
particle to the outside world didn't affect transmission through "silver
dope" UV protectant to any measurable degree. However, carbon black is not
a reflector, but an absorber. Signals don't get reflected in carbon; they
get converted to heat and absorbed. That ain't rocket science; that's what
I teach to my freshman engineering students. Is that understood?

You folks that are paying tens of thousands of dollars for your kits need to
have your vendors take my freshman engineering class.

Jim



--
"If you think you can, or think you can't, you're right."
--Henry Ford

"Morgans" wrote in message
...

"Sliker" wrote in message
...
On the older Glasair kits like mine, it's covered with the dark gray
gelcoat that contains 2% carbon black for UV resistance. I wonder if
the carbon interferes with radio reception? I've read that cabon fiber
structures block signals, but how much carbon it takes to do that I
don't know. But for the Glasair folks to say the radios worked so much
better when the moved the antennas outside, makes me think some part
of the structure was blocking radio signals..

I could be wrong, but I recall that Jim Weir has done extensive testing on
airplanes, and what structures block radio signals, and carbon fiber has
been found to not be a problem. I hope I remembered right, and Jim will
probably jump in here and clarify the situation.

When it comes to antenna mounting and performance, I think we are lucky to
have a resource such as Jim to help us get on the right path. He is an
expert on the subject, IMHO.
--
Jim in NC