the antenna is a dual band, so each cable has a 2.4 and 5 Ghz antenna. the MR76 has both 2.4 and 5Ghz on each port, so every antenna port is exactly the same and you can connect the antenna cables wherever you want. you can connect a second antenna aimed exactly the same for MIMO service, or pointing a different direction for extended coverage width (sectors). the MR74 has separate antenna ports, 2 ports for 2.4 and 2 ports for 5Ghz. one could be used for vertical and the other port of the same frequency for horizontal polarization