UHF Aerial Location

Submitted: Saturday, Apr 13, 2002 at 00:00
ThreadID: 956 Views:2200 Replies:6 FollowUps:3
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The "experts" tend to recomend that the best spot to mount a UHF aerial is on the roof/gutter of your vehicle.
Given that this is impracticle ( height constraints)what would be the best multi purpose ( if there is such a thing)aerial config. for a bullbar mount.
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Reply By: Dave - Saturday, Apr 13, 2002 at 00:00

Saturday, Apr 13, 2002 at 00:00
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.
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Follow Up By: Donalddasher - Saturday, Apr 13, 2002 at 00:00

Saturday, Apr 13, 2002 at 00:00
i have a gme tx4000. what is ground plane independant??
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Follow Up By: Dave - Saturday, Apr 13, 2002 at 00:00

Saturday, Apr 13, 2002 at 00:00
have a look at the GME website

http://www.gme.net.au/land/land.html

They don't go into a lot of detail but the info you find there may help
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Reply By: Andrew Donald - Saturday, Apr 13, 2002 at 00:00

Saturday, Apr 13, 2002 at 00:00
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.
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Follow Up By: Bill - Saturday, Apr 13, 2002 at 00:00

Saturday, Apr 13, 2002 at 00:00
Just one thing to add - an aerial which is ground plane independent will have a section between the aerial and its base. Sometimes this is a chrome tubular section say 6 inches long and sometimes a small black piece about the size of a cotton reel. Allegedly any mounting other than the centre of the roof requires this type ... however I have a friend who has a wire aerial on an ordinary base mounted at the side of his bonnet and it works fine.
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Reply By: slunnie - Sunday, Apr 14, 2002 at 00:00

Sunday, Apr 14, 2002 at 00:00
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.
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Reply By: Kev - Sunday, Apr 14, 2002 at 00:00

Sunday, Apr 14, 2002 at 00:00
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.
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Reply By: Nigel - Tuesday, Apr 16, 2002 at 00:00

Tuesday, Apr 16, 2002 at 00:00
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.
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Reply By: Rob - Tuesday, Apr 16, 2002 at 00:00

Tuesday, Apr 16, 2002 at 00:00
This site is a good information source http://www.alphalink.com.au/~parkerp/cb.htm
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