Hi Jean-Luc and Andy
Many thanks for replying. This build just goes to show that you can never take anything for granted in modelling! I should have known better by now, but I thought positioning the aerials would be the easy bit... :-)
Andy - many thanks for the link to José's beautiful model. I have to say I think he's mis-interpreted the reference photos as regards the lower aerials being positioned behind the drop tank.
The following pics will explain my quandery. Eagle Editions have very generously sent me a copy of their stunning book - JG 300 Vol. 1. (This is going off-topic but, suffice to say, this is far and away the best reference on this unit I've ever seen and I'll be reviewing it very soon.) Anyway, in the book is a pretty clear photo of the aerials under the starbord wing of one of the unit's A-5s:

This seems to be backed up by A.L. Bentley's classic drawing drawings which appeared in Scale Models way back in 1978 (hence the nicely yellowed page!):

Strangely enough, José depicts the aerials in this configuration on his 1/72 scale Academy kit.
But here's the fly in the ointment. :-) I'm basing my build on an original TriMaster Fw190 A-8. It's actually "A-7-ready" in terms of the mounting holes for the pitot tube etc... and it must have been released as a nightfighter at some point, because it has the positions marked for the aerials. The trouble is, on the underside, it has two sets of angled aerials (sort of mirroring the upper-surface configuration)!:

I guess, if nothing else turns up to the contrary , I'll go with Mr Bentley.
All the best
Rowan