BCM4312 has 2 radio chains, one is a dedicated Rx chain, the other is shared by TX and > RX chain using an RF switch Support Antenna Diversity
RF Output Power 802.11b: 16.5 dBm ± 1.5 dBm 802.11g: 15.5 dBm ±1.5 dBm
Can I hook up two Yagi antennas to each u.fl connector (it has 2 u.fl male connectors) and will "diversity" work? How exactly does all this work?
Spatial diversity employs multiple antennas, usually with the same characteristics, that are physically separated from one another. Depending upon the expected incidence of the incoming signal, sometimes a space on the order of a wavelength is sufficient. Other times much larger distances are needed
Transmit/Receive diversity uses two separate, collocated antennas for transmit and receive functions. Such a configuration eliminates the need for a duplexer and can protect sensitive receiver components from the high power used in transmit.
All of the above techniques require some sort of post processing to recover the desired message - Switching – In a switching receiver, the signal from only one antenna is fed to the receiver for as long as the quality of that signal remains above some prescribed threshold. If and when the signal degrades, another antenna is switched in. Switching is the easiest and least power consuming of the antenna diversity processing techniques but periods of fading and desynchronization may occur while the quality of one antenna degrades and another antenna link is established.