Dave replied:

I'd go with (and have myself for work vehicles and for my own) with the GME range of interchangeable aerials, they are Ground Plane independant and for my money are the best around, of course if your unit isn't up to scratch then the best aerial in the world, regardless of where it is mounted won't make a diference. I have my aerials mounted on the left hand side of the bar so that they do not obscure vision.

I have the huge 6ft (4706 i think) on my truck most of the time. It has copped a caneing many times and the fibreglass isn't even badly scratched.

Andrew Donald replied:

Donald, (somebody correct me if I'm wrong) The ground plane is the effective surrounding of metal that the aerial uses for a ground plane. When the ground plane is evenly distributed on all sides of the aerial then you will have an even spread of signal "from" the aerial (not sure about "to" the aerial). So that's why they reccommend the centre of the roof as the best spot. But you can get aerials that are ground plane "independant" so it has little effect where you mount them. Hope this helps.

slunnie replied:

I have also used the GME 4700 series interchangable setup which is brilliant. The system will allow you to run different aerials depending on where you are or what you are doing. I run the GME AE409L(6&9db wire type and very bendy, depending on setup) on this set up around town and it hasn't hit anything yet (bullbar mount). In the ruff stuff it takes a range of fiberglass aerials on a good spring base which seem to resist damage really well (I've had the AE4706 2.1m 6db aerial almost flexed back to my roof before). These are all are ground plane independant - its transmission pattern is not affected by their mounting position. The other aerial I use for the bush is the AE4705 4.5db, which is about 1.2m and is very good in the bush. With this aerial I still need to remove it before entering a lot of covered areas.

Kev replied:

G'day boys and girls just a quick tip. I have covered my 6foot fibreglass aerial with HEATSHRINK this makes it even more durable and does not seem to interfear with the signal.

Nigel replied:

a quarter wave (12cm) antenna in the middle of the roof seems to be the best all round option, but not many people want a hole in their roof. if you move away from the centre of the roof to the gutter or bullbar, then a ground plane independant setup will give you more even coverage. A standard aerial will still work, but you will transmit more to the rear than the front (if it's on the bullbar) and receive better from in front of you than from behind. but even with ground plane independent setups you need to keep them away from vertical metal areas (eg the A pillar or other aerials) or it will affect your signal. make sure you buy a good brand (GME, RFI, Mobile One, Polar) with quality coax or it won't matter where the aerial is.

Rob replied:

This site is a good information source http://www.alphalink.com.au/~parkerp/cb.htm