Tezmand,
Gogg is on the money - have a look at this pic - it shows you exactly where its located (its from a German web site - but none the less, its self explanatory)
I think you can buy an after market booster kit for the aerial - Im not car techincally minded, but others on this forum are...come in SiJ2000!
Anyway, have a looksee.
All the best,
David