I'm no pro with electronics, so not sure if it matters (I like to tinker, so it doesn't hurt my feelings if it won't make a difference) but I made an external aerial of the correct scale length (StuG III) and plan to use that, connected with an internal antenna, to keep the overall antenna length "stock". If nothing else, the visible antenna is not only historically correct, but functional, giving it a reason to be there.

Made up lengths, but for example: if the stock HL antenna is 18", and the scale StuG aerial is 6", the 12" difference will be made up with the internal antenna mod.