As far as I can tell, the Enterprise's navigational deflectors are spherical. Otherwise she couldn't accelerate in full reverse or do warp pivots or later on in the movies fly around V'ger.
Well, I guess I should have qualified which sources I meant. FJ has the navigational deflector on the main dish, and that faces only forward. Memory Alpha concurs: http://en.memory-alpha.org/wiki/Navigational_deflector
It's very difficult for me to reconcile the idea of a dish that aims in a particular direction with the idea that deflector beams can be directed in any direction with equal ease.
But what of the Reliant? Or the older ships like the Aurora Space Cruiser? They don't have a dish.
The first time the "dish" = navigational deflector on screen I think was in TNG with the E-D. I just view that as a limitation of the E-D and ships that used that design philosophy which the TOS Enterprise, movie Enterprise, Reliant, Stargazer, etc did not follow.
I know! I have no certain answer to that.
's world, ultimately Star Trek
breaks down. I mean, honestly, I try to take it as far as I can, because I enjoy Trek Tech. But this is an example at the frayed edge of the tapestry that is Star Trek.
I can reach into my bag of tricks and postulate that there are different classes of navigational deflector systems. Perhaps there is a low power system that works well enough for certain classes of maneuvers that doesn't require a dish? That would mean that the heavy cruiser connie can just plain do more, such as:
The Paradise Syndrome
uses a deflector beam from the Enterprise.
IIRC, the original effects didn't show where the beam came out of, but the remastered effects have it coming out of the dish.
remastered FX: http://tos.trekcore.com/hd/albums/3x...romehd0510.jpg