Mounting uhf antenna on aluminium bulbar

While not a expert, I am pretty sure UHF Antenna's are ground independant & do not require Earthing !

I just mounted my UHF onto the mounting hole on the aluminium bar and it worked fine.
The antenna works better if you mount in the middle of the roof but who is going to cut a hole in the roof just to get an extra Kilometer range out of a UHF.

Hi,
they work perfectly mounted on alloy bars; the antenna is ground independant as mentioned above.

kc

Two factors involved here -

1) The outer of the antenna lead must be well grounded to complete the electrical circuit. Assuming the aluminium bull bar is firmly attached to the vehicle, that's fine.

2) This antenna is NOT a ground independent one. It relies on having a decent sized reflector (a ground plane) close by to provide a mirror image of the antenna, effectively doubling it's size as a radiator. It will work to some extent without a ground plane, but much better with one. Mounted on the bullbar, the bonnet will provide that ground plane. You do not need to provide any special electrical connection, just that large area of metal which acts as a reflector at these frequencies.

HTH

John

Hi kcandco, I think your question has been answered well by others, but just to reinforce the answers, aluminium is used as an earth cable for weldering machines that require long leads, due to the difference in weight, makes them so much lighter to carry, so don't worry about having an aluminium bar, it will earth just fine. GROUND plane is not the same as EARTH,
it is to do with the surrounding geometrical plane, that affects the reception/transmission of the radio 'waves'. Well, thats the way I understand things, am prepared to stand corrected if I'm wrong. 'Whacker

Be sure you have a good quality aerial and a spring base to attach to the bullbar.

Bullbars move independently of the vehicle body and have a tendency to shake inferior aerials to pieces, especially on corrugated tracks.

Bill.

Thanks Everyone Now I feel like I'm on the right track. I was thinking the ground plain must have a physical connection to the base of the antenna, but this apparently is not the case. My next concern which I hadn't considered is how my antenna will stand up to vibration on the bullbar? I guess only time will tell.

regards Kc

just try it out with a friend in another vehicle and you will soon know if it delivers what you want. UHF is not going to get too many chances to obtain a long line of sight with all the bush, hills and buildings and get you much more than you need. Remember that uhf is intended to get close comms and not all the other traffic out there in the ether. The old 27 meg used to jam up with stuff from all over the world when the atmospherics made it work like HF. 27 is so close to the vhf band that it behaves sometimes like hf and sometimes like vhf. UHF was never meant to be long distance and that gives you an idea of why it runs on so little power.

Owen

You really need a Ground Plane Independant antenna to mount on a bullbar - even if you run a wire from the bullbar to the bodywork, there's no connection from bodywork to bonnet except at the Latch.

You still don't have any groundplane in front of the bullbar.

KC
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