homemade external/internal antenna for handheld.

The subject sort of tells most of what I'm looking for. I have an
Aeronca and would like to increase the trans/recep of my handheld.
There was an article by Weir a couple of years ago in Kitplane, I
think, on how to make one.

Help?

Thanks

Mark in third world Wyoming.

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.

gorgon wrote:

The subject sort of tells most of what I'm looking for. I have an
Aeronca and would like to increase the trans/recep of my handheld.
There was an article by Weir a couple of years ago in Kitplane, I
think, on how to make one.

Help?

Thanks

Mark in third world Wyoming.

("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

In article ,
"Montblack" wrote:

("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?

What can I say, it worked like a ..... Champ!
Rx and Tx with an ICOM A2 and A20 on low power (1/2W) was sufficent for
most operations. I could talk air-to-air with friends 35nm away. Can't
do that with a rubber duck!

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

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

("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.


(John Smith wrote)
"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."


1. With a standard handheld, what would the average length be (approx) for
the rod(s)?

2. Should the rod be insulated, at any contact points within the wing? If
yes, with what?

4. If no, does the rod cantilever away from the BNC connector, without ever
touching anything else inside the wing?

5. Does the length of the coax (running to the radio) matter,
significantly?

6. Is there a benefit to having one wing 'tuned' to receive and the other
wing 'tuned' for transmitting? g


Montblack

RST Engineering wrote:

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,

Not being on the mailing list of the Puget Sound RV8ers I think such an
article in Kitplanes would be a great idea as do probably many other
non RV builders. Thanks and I'll look for it in future issues.

Don.

In article ,
"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.

True, but this was a time-saving step.
(Red/white striped package, cannot remember the manufacturer. Larson?)
It was a HAM antenna base. Punch a 1" hole in the metal, unscrew the cap
from the base, insert base through hole, screw on cap. Whip set in a
well in the cap and secured with a set screw. The base had the coax
attached at a right-angle and fit the shallow area between the top and
bottom fairings.

"Montblack" wrote in message
...

1. With a standard handheld, what would the average length be (approx)
for the rod(s)?

It is a function of rod diameter. With an infinitely small diameter wire,
the length for each rod would be about 23.2" for a geometric (*) band center
of 127 MHz. With a half-inch diameter rod, that would reduce to 20.2 and in
between is in between. (*) The geometric center of the band is the square
root of the (bottom end of the band times the top end of the band).



2. Should the rod be insulated, at any contact points within the wing? If
yes, with what?

Electrically, no. Mechanically, probably. A nylon cable clamp would work
well.



4. If no, does the rod cantilever away from the BNC connector, without
ever touching anything else inside the wing?

It can. However, vibration will eventually take its toll.



5. Does the length of the coax (running to the radio) matter,
significantly?

It does not matter at all. An old wive's tale says that there is a "magic"
coax length. Put an orange in the center of your house and start running
around the outside. You can see differences in the orange depending on what
window you look through, but you never get any closer to the orange no
matter where you are relative to it.



6. Is there a benefit to having one wing 'tuned' to receive and the other
wing 'tuned' for transmitting? g


Why? They are both on the same frequency.

Jim