If its really an electric one your after ignore this....
but when i got my spec 1 r33 gts-t the arial was snapped off. I went to local car shop and looked at all the ones they had for diferant cars and a roof mounted one for a little shopping trolly (might have been a corsa) had just the right angle on the mounting gromet thingy. £5 works a treat and looks ok i think.
Simon