Effect of Antenna Polarization Diversity on MIMO System Capacity

The effect of circular polarization diversity on the capacity of a multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system is investigated based on channel measurements. In this letter, polarization reconfigurable U-slot antennas are incorporated in a 22 MIMO-OFDM demonstrator, and the channel measurements are conducted in both line-of-sight (LOS) and non-LoS (NLOS) indoor environments. Measured results show that transmit/receive antennas radiating different polarizations are able to improve the system capacity significantly compared to antennas with the same polarization in a LOS scenario, while the extent of the improvement is reduced in a NLOS scenario. Furthermore, the factors that can affect the system capacity in both scenarios are analyzed.