Jim,

That article has already been done by a local RV-4 builder several years
ago. I published it in the Puget Sound RVators.


WING TIP ANTENNA INSTALLATION
by Greg R*****
Puget Sound RVators

I have heard of a few stories told of people who tried communications
antennas installed inside the wing tips on their RV's. All of these
stories told of how it did not work and was abandoned. These stories
all had two things in common. They were all told to me second, third or
fourth hand and they all included many theories as to why antennas
located in the wing tip should not work well. The two primary theories
were "it has to be vertical" and "it will be blocked by the airplane".

During my job as an avionics technician and my 25 years of antenna
building "for the fun of it" as an amateur radio operator, I have
learned to take antenna theories as a rough starting point only. There
is nothing like a successful installation to show that antennas are a
bit of a black art!

With all this said, I would like to describe the simple communications
antenna installation that I have been successfully using on my RV-4 for
the past 60 or so hours. This antenna is easy to construct, is very
cheap (mine cost coax only, as I had everything in my junk box) and
works well for me. It consists of 4 parts: a length of RG-58 coax
cable, one SO-239 coax connector, one PL-259 coax connector and one coat
hanger. The coax and connectors are available from your local Radio
Shack and you can raid the hall closet for the hanger!

The SO-239 is a female, bulkhead type, coax connector and requires one
large hole and 4 mounting screw holes. I placed this connector at the
very forward end of the outboard wing rib (mine is on the right wing,
either wing would work as well). The center of the coax is soldered to
the center pin of the connector. The shield should be tied to one of
the flange mounting screws using a terminal lug and a piece of sleeving
to prevent it from touching the center pin. (See sketch)

I have Aeroflash strobe power supplies mounted in each wing tip.
Although the whip passes close to the high voltage lead from the power
supply to the strobe I experience no interference. Those with central
strobe power supplies that have high voltage leads down the entire
length of the wing may have a pulsing interference problem if the coax
is routed near the strobe wire for very far.

I have had very good luck with this installation and it shows very
little blocking for stations off the opposite wing. In fact, this has
proved to be no problem at all. If you have any questions regarding
this installation, feel free to call me at 206-353-****. For those who
would like to see the installation, sorry, it's hidden in the wing tip!




RST Engineering wrote:
You could have saved yourself half the price of the "commercially available
antenna base" by using a bulkhead BNC female connector, mounting it to the
same piece of aluminum and feeding one side with connector/coax to the radio
and the other side with a BNC connector on the other side with a brass
brazing rod of your choice in diameter for the radiating rod.

Would this be a good Kitplanes column? I know I've made passing reference
to this lashup before, but perhaps not in enough detail.

Jim



"Montblack" wrote in message
...

("john smith" wrote)

I purchased a commerially available antenna base and had it mounted to a
piece of the aluminum where the left wing meets the fuselage. A doubler
plate was riveted to provide extra strength. A length of stainless steel
rod cut to mid-frequency length was inserted to serve as the antenna. This
was on a 7AC. The antenna coax entered the cabin at the leading
edge/canopy junction.


Did this arrangement have some strong points and some weak points -
reception wise?

How were the results, overall?


Montblack