Hi Jim

Keep in mind that if you are doing a lot of off-road the high gain
antenna, normally optimized to radiate towards the horizon, ends up
skying or firing most of it into the ground. This is why for example a
1/4 wave is great in city "canyons" and mountainous areas. The "all
around" radiation has a better chance of reflecting off something above you.

You can always make a wire etc counterpoise for the 1/4 wave.

Any effective collinear is going to be big to do well. Its also going to
be somewhat whippy. A 1/2 over 1/4 or 5/8 over 1/4 you can work out how
big that will be. This kind of antenna will need a ground plane so maybe
you could look at a 1/2 over 1/2 voltage fed. This will be over 6ft long!

I saw a 1/2 wave voltage fed antenna once made up like a slim jim. It
had two parallel spring steel conductors about 4-5ft long and half n
inch apart. It was very effective. It was fed about 2" from the bottom
(the lower 1/3 of the antenna being the matching section - which also
raised the antenna height some) If you want to experiment (with
something that will eventually break) consider some 300 ohm ribbon
inside 3/4" plastic conduit.

Apologies for not giving any specific brand details. I tend to make my
own...

Cheers Bob VK2YQA

James wrote:
I want to mount a 2 meter rig on my Honda Foreman ATV. I want a
high-gain antenna, either a 5/8 wave or possibly a collinear. I would
like to stay around 4 to 5 feet in length, but it is possible that a
collinear would be longer.

A good choice for vehicles without adequete ground plane would be the
!/2 wave end fed antenna that does NOT require any ground plane.

One such antenna he www.comtelco.net A1812A 44

Also can be orderd with the heavy duty .125 dia whip, The whip is about
39" tho.

The radiation pattern is the same as a 1/2 wave dipole and much the
same as the
1/4 wave whip.

"Will" wrote in news:1163889515.013109.230270
@h48g2000cwc.googlegroups.com:

A good choice for vehicles without adequete ground plane would be the
!/2 wave end fed antenna that does NOT require any ground plane.

One such antenna he www.comtelco.net A1812A 44

Also can be orderd with the heavy duty .125 dia whip, The whip is about
39" tho.

The radiation pattern is the same as a 1/2 wave dipole and much the
same as the 1/4 wave whip.


That antenna is a pretty good choice. I'd add that if Jim wanted to
try a 1/4 wave it might work, because he could catch a ground plane through
the frame. That is where most mobile antennas get their "ground".

- 73 de Mike KB3EIA -