CB Aerials

Why aren't you working. Whats a Dipole??

I realise that the best place is smack bang in the middle of the roof (all metal), but there's a roof rack. Side gutter mounting is the same principals as front mounted.

Jeff, would a UHF work with a long wire antenae?... just curious.

Nudenut, nah mate, well I mean if you had a UHF SWR meter (costly) you could probally cut a small peice of wire to the correct length (approx 70cm) however it would not be a very good antenna.

Jef ...a long wire is exactly that or so I thought....eg.many multiples of the wave length say 30metres long or there abouts?

The height is a biggy. Neighbour and i have identicle set ups. I have gutter mount and he has bull bar mount. I get a lot better range than he does. (a lot better)

The Brewman

No the same principle wouldn't apply. Well technically it kind of could but in practice it would be very difficult.
27mhz AM/SSB CB was more similar to HF that UHF. It had a wavelength of 10m. UHF is around the 70cm park. Hence there is a lot less margin for error on UHF than there is on 27Mhz. ie 27mhz vs 477mhz.
The twin ariel I have never seen but I would assume it was a dipole. We used to make them out of 10m of coax and a film canister in the middle. Hang them between a tree and the house, they were cheap to make and worked a treat! However dipoles for UHF are a hell of a lot smaller, ie I have one on my surf that just looks like a car radio arial about 30cm tall and just black rubber style job.
The other thing was that with 27mhz we were trying to get "skip", that was the whole aim of make and positioning the ariels however "skip" is practically non existant on UHF. Height is the key. UHF does have somthing similar (well to the average joe, very different technically) called "induction". Induction normally happens from environmental conditions and tunnels UHF signals down the coast. EG might be able to talk from bunbury to geraldton. But these are almost impossible to predict and you cannot really set your radio up to take advantage of it as such.

I canunderstand the want/need for a slightly better range out of UHF, when it the bush doing tracks in large convoys you can get quite large distances between the leader and the charlie, especially if there is a lot of dense scrub and hills. Obviously you can use others in the group to repeat messages to the back, but it's not ideal.
I think that changing to a lower DB antenna would be part of a solution for this, I mean in reality the higher DB antennas are better, however it's not very often that we are all on the nullabour trying to communicate. Normally there are hills and building, bush etc in the road and the lower DB would probally help. The other option is to have two antennas and a coax switch, one higher DB and one lower DB so you can get the best of both worlds, however these would drain some of your output power. There are obviously antennas out there that you can adjust the DB rating by putting different tops on them, however from memory these are only 6/9/12DB. I would expect you would want to try somthing like 2.5 to 4.5DB.