Thread: UHF Antenna location

Originally Posted by Ranga

I spotted a forum member's antenna the other day located in the middle of his Defender roof. Anyone care to comment of the pros/cons of antenna location?

I asked a similar question some time ago. It would come up with a search. I will try to relate my understanding from that query. If the antenna was not ground plane independant ( and most on the market now are ) the centre of the roof is a good spot, and provides an ideal reflector, and good height. The same applies for a ground plane independant antenna, but in reality it doesn't need that big flat roof as a reflector, just the height.

One potential consideration for a roof mounted antenna, is the type of construction. Probably not a good idea to have a super rigid antenna up so high, if your trekking includes scrub work.

I am currently looking at mounting my antenna on a pedestal on the spare wheel carrier. ( very much like the current VHF setups ) It was to have been mounted on the roofrack, but this became inconvenient for loading, and now I also intend to remove the rack between trips.

The current thinking seems to be, use a ground plane independant antenna, and get it as high as practicable.

Yes, everything said above is correct.
At UHF no matter what aerial you have, the higher you can get, and clear of other vertical metal, the better. But it's always a compromise for those that go into forested areas.

Ranga you could have just asked me, and i would have said exactly the above !

mount it on the roof with a good spring base and trees and shrubs are not a big problem but car parks are still a pain you smash all their fluros

Centre of the roof is the ideal position from the communication point of view. But is the worst possible position from the point of view of overhanging trees and carparks, carports, garages etc.

Balance these pros and cons and make your own decision. For what it is worth, both my Landrovers have them on the bullbar. Not ideal, but won't get overhanging trees etc and you can see what they are hitting.

John

Originally Posted by JDNSW

Centre of the roof is the ideal position from the communication point of view. But is the worst possible position from the point of view of overhanging trees and carparks, carports, garages etc.

Balance these pros and cons and make your own decision. For what it is worth, both my Landrovers have them on the bullbar. Not ideal, but won't get overhanging trees etc and you can see what they are hitting.

John

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And a high gain antenna is best out in the open areas as it propagates the signal out horizontal more than up.
So high gain like 12db is good for open area etc, but not so great in hilly areas. a smaller gain antenna of <6 db is better suited to hilly terrain. So if u have spare $$, and spend time in each terrain, u would benefit from swapping them around.
(If u could be bothered)

Seen a few Disco's with a mount for the aerial constructed/located on the rear wheel carrier. Last one looked like the rfi cd9000 6db....
Any thoughts on this position...
James