i suspect it runs towards the passenger side and then through the upper part of the roof on that side under the plastics and then down the passenger A piller, behind the glove box and to the radio.
Altho, to perform a check for this...the glove box and assembly around it come off pretty easy..just a couple of screws...so you can remove it and have a look for the aerial ther to see whether it is travelling in at that side...if so..then that gives you a means to track its pathway to the rear;-)
