You don't seem to understand. In ROTJ, there seems to be a clear connection between a flight of A-Wings taking out the radome, and an Executor bridge officer reporting that the shield strength is falling.
In the books, they are referred to as shield generators. In the absence of in-movie information to the contrary, these structures are, canonically, shield generators.
Remember that their actual function is nowhere stated exactly. Conjecture by model builders, unless confirmed in a canon source, is not canon.
You can argue it both ways, I suppose. All we have is conjecture on this point. However, since there is one interpretation that is common throughout the Expanded Universe, it would be weird to suddenly contrdict it, IMHO.