To take full advantage of MIMO (currently used in 4G LTE communications) two antennas must be used. When installing directional antennas like a panel antenna, the first antenna must be rotated horisontally to a 45 degree angle and the second to a 135 degree angle. This is because of "polarisation diversity". LTE uses polarisation diversity to help distinguish between the two data streams sent from the tower.   This MIMO panel antenna for 3G has the advantage of good isolation between the two ports.