Sorry for my ignorance, but will a replacement make my radio signal any better as it is currently rubbish 
Thanks
+1
I think you need the base and not just the antenna..
I thought it was a sealed unit?
It is a sealed unit kind of. If you've got problems with poor radio reception and you've eliminated connections in the front of the vehichle and head unit, this is what I did:-
1) Undo the screws that secure your roof lining in place, be careful here, mine was fine, but a friend said the boot lining can lose its shape and sag if you force it down too far.
2) Undo the bolt securing the antenna base to the roof, if I remember correctly there's an earthing washer that cuts into the metal of the body work, check this earth is good with a multimeter.
3) If you have a powered antenna base like mine you'll have a 2mm wire going to it as well as the coax cable, this supplies the current for the amp circuit (the negative comes from the car earth). You'll need to cut this wire and insulate the powered end of it once you've established that your amp circuit is blown. I think the coax cable has a connector not far from the antenna base.
4) There is a rubber base to the base of the unit, I can't remember how its attached but I remember this stage slowing me down, I did manage to prise it off eventually and cos its made of rubber and I was careful it still looks A1 back on the car.
5) Now you should see the polystyrene looking material that fills the base, its there to stop water getting into the amp circuit, you just gouge all this out until you can see the circuit.
6) My circuit looked visibly damaged, blackened in places I think
7) If I remember correctly I then just cut the circuit out with wire snips at the top and bottom, then I think the wire that connected to the bottom end of the circuit was long enough to bridge the gap to the top of the unit where I soldered it to the connector for the mast screw fitting completing its connection to the coax. So your removing the to wires I think to the amp circuit, and bridging a single wire connection for the coax (the signal cable)
This makes it basically like any passive bee sting antenna. ie it works ok but not as good as a standard 1M steel one.
but hey, who wants to replace their antenna every 6 months? :-)
