[kg4kpg]

When you calculate your length do you measure the length of the wire strait or after it was wound?
Also, on semi's it's best to run co-phased antennas since we can't mount in the center of the roof for a good ground plane, I assume the same would be true for the Jeep, when we were tuning Amy's new cb we got some odd swr readings. and her signal is much stronger to the front than the rear or sides.
Can you run co-phased 2 meter antennas? think it would make much difference?

I haven't seen dual 2m antennas before, that I can recall. I'll have to ask about that. On my 2m antenna I had to trim a little from the tip, if that's what your asking. When I built the 70cm antenna I started out with a measurement someone gave me and turned out to be exactly the lenght I needed, no tuning required.
Oh, looks like I have the avatar you need.

 

[kg4kpg]

On the one I made it was the wire length. In 2m fiberglass antennas it is the wire length from what I understand. There is usually a lot of wire wraped at the bottom then just a few coils as it works up to the top.

 

[kg4kpg]

I got a reply from a ham on QRZ.

"The antennas would need to be much closer to each other than that for co-phasing. Besides, co-phasing isn't a good idea for a mobile radio, in general. It works well for the truckers; because, they drive down the road in a line, one in front of or behind the other. Co-phased 1/4 wave CB whips provide a bi-directional pattern, aligned front to back with the vehicle. That's great, if you want to talk to another vehicle on the same road either in front of or behind you, but it's lousy in almost all other instances."