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.