what does the radio do with two antennas, does it add the signal on two antennas? or does it have two modem chains for each antenna? can i connect two directional and point them in different directions? or does it subtract the signal from each other in order to filter out near by interference?
802.11n wireless standard makes use of both antennas to gain better speeds. The technology is called MIMO (multiple in multiple out).
There are other ways to use two antennas at the same time.
they are on .11g cards too and i don’t think mimo is not part of .11g
802.11n is an improvement upon the previous 802.11 standards by adding four multiple-input multiple-output antennas (MIMO), the previous 802.11a/b/g standards allowed only one MIMO stream.