I see. Mr. Probert could answer better, but I imagine that there's a comprehesive grid of emitters such that the whole ship seems to disappear at the same time. Whether the main central device is at top or bottom wouldn't have anything to do with the visual effect, I suppose. The cloaking devices that have been shown, in fact, were relatively small. no larger than a casket. (Refer to DS9: The Emperor's New Cloak.) Maybe I'm not being very helpful.
And thanks, guys, for the helpful information. All 54 of these things are getting stuffed into a software package for release sometime today. The testers are happy, and the users should be, too.
And thanks, EmperorTiberius, again, for spotting that transposed number on the Saber class schematic a few days ago.