After doing some more research on 900MHz flat panel options, I found this antenna made by mimomax.com (PDF spec sheet included) which at first glance looks pretty amazing specification-wise... dual-pol, 16dBi gain all in one flat panel package! Hmmm... what's the size? 3 feet wide, by 1.6 feet tall and 2.3 inches thick. Talk about a billboard!
Everything that I've found is big and/or ugly, and a lot of it isn't really tuned for 900-930MHz... most of the antennas I end up find are tuned for a wider range, or lower band like 800MHz because they're really meant for use with certain cellular carriers.
You could just use two separate patch panels (or two monster 17dBi yagi's!!) which would give you a bit more spatial diversity (possibly a slight boost in performance depending on how far apart they are) at the cost of slightly more attenuation introduced by having to use longer RF jumpers and adapters. It might just be a wash though.
- 900-MHz-Panel-Antenna-Spec-Sheetv4.pdf (1.34 MB)