How do I improve my Groundplane?

If you have an aluminium roof and cannot get a good SWR reading on your antenna (click on 'what is swr' above if you havent already) then your groundplane is probably to blame. To improve your groundplane you can do one of three things, the first is the easiest and cheapest;

 

1) Run a wire from the antenna mount to the chassis of the vehicle. The wire needs to be as thick as is possible, anything over 10amp rated is suitable. Make sure it is attached to the ground part of the mount. This normally works fine however if it doesn't you may need to look at the next suggestion.

 

2) Attach a metal sheet or plate underneath the mount, if the antenna is mounted in the roof then a metal plate underneath the mount is best. You can use steel or even copper for this. The bigger the plate the better, make sure it is at least 1 foot square. You will probably find that running a wire from the plate to the chassis will also help.

 

3) Use a ground plane kit, these come in two types. The first is a simple kit called an ERF kit, designed originally to fit to the mirror arms of ERF trucks(as the cabs are made of fibreglass). The kit has a metal rod underneath it so will only fit onto a mirror arm etc. with room underneath it. The second is an Electronic groundplane kit with can be fitted somewhere more practical as it is smaller, i.e. the roof rack if you have one.

 

Click here to see both types.

Groundplane Introduction

Groundplanes can cause trouble even with the best CB setup, if your groundplane isn't very good then your antenna will not perform as well as it should. A Groundplane is needed for any CB antenna to work, without it the antenna will not transmit very well and your SWR reading will probably be very high.

What is a Groundplane?

Most metals make a good groundplane material. However not all metals do, even though aluminium is a very good conductor it is not a good groundplane. This is a pity as most landrovers have aluminium bodywork! Steel works extremely well so if you are mounting an antenna in a car or lorry roof then you normally don't run into any problems.