Homemade Antenna

[Carl J. Hixon]

I am looking for information on building a home made antenna. Months ago I
found myself quite accidentally at an ultralight club meeting in San Diego.
After the meeting they were having an antenna workshop to build some
antennas for their ultralights.

The antennas were made out of coax cable and a BNC connector. It was more
of an L configuration than a J-pole. If I remember correctly, they took
several feed of coax, stripped off shielding and insultation on some of the
long leg as the radiator and connected the other end to a tee BNC connector.
On the branch of the BNC connector, they used about 2-in of coax. The
feeder line when into the other "straight" side of the BNC connector.
(Initially they weren't using the BNC connector, this was an 'improvement'
in manufacturing because it was difficult to solder the copper and keep the
shielding separate, etc.)

I know that is a fairly poor description but, does anybody know what I am
talking about and where I can get plans?

Thanks,
Carl

[[email protected]]

Ok, here is some info....

An antenna for 122.8 or thereabouts is about 2.45 meters full wave. A
vertical quarter wave is typically 50 ohms with a ground plane. A
quarter wave is .58 meters or 22.9 inches. If you use the airplane as
the ground and place a 22.9 inch antenna that is somewhat vertical from
the fuselage you might have it. Use 50 ohm coax to the point and ground
the shield to aircraft chassis at that point. Test the SWR (standing
wave ratio). It should be 1.5 to 1 or less. An 'L network' may be
needed to tune out any reactance. This is an experimental antenna ONLY.
A local ham club could really help out in testing the antenna. THeir is
something called an MFJ Antenna Analyzer that will tell you the
resonant frequency of the antenna and its impedance.

A well matched antenna should do fine with just 2 watts of output.
There are other types of antennas that could be used but the 1/4 wave
vertical is easy.
You will probably want to slant the antenna back at 30 degrees or so.

The above information should not be used for aviation communications
and is for experimental purposes only.

Rob
NV7F

[Robert Bonomi]

In article <5p1dd.49656$hj.8045@fed1read07>,
Carl J. Hixon > wrote:
>I am looking for information on building a home made antenna. Months ago I
>found myself quite accidentally at an ultralight club meeting in San Diego.
>After the meeting they were having an antenna workshop to build some
>antennas for their ultralights.
>
>The antennas were made out of coax cable and a BNC connector. It was more
>of an L configuration than a J-pole. If I remember correctly, they took
>several feed of coax, stripped off shielding and insultation on some of the
>long leg as the radiator and connected the other end to a tee BNC connector.
>On the branch of the BNC connector, they used about 2-in of coax. The
>feeder line when into the other "straight" side of the BNC connector.
>(Initially they weren't using the BNC connector, this was an 'improvement'
>in manufacturing because it was difficult to solder the copper and keep the
>shielding separate, etc.)
>
>I know that is a fairly poor description but, does anybody know what I am
>talking about and where I can get plans?

Nope. not a _clue_, based on that "description".

See the "ARRL VHF antenna book" for (probably) more than you want to know,
about building your own antennas.