Bigboywooly - like Txema said it's round radio, not radar antenna. Radar antenna is rectangular (except of FuMO29) and should be placed at left side of conning tower, in special recess (you can see it, when you choose type VII/1945 in any single mission, this recess is empty, but antenna is placed at face of conning tower
).
If you want a pic, look at this:
http://www.paolopizzi.com/paolopizzi...eix/typeix.htm
see "active radar" section, first photo is FuMO29 antenna (well implemented in SH3), next two photos are rectangular FuMO30 and Hohentwiel antennas.