How Low Does Mutual Coupling Need to Be for MIMO Antennas

MIMO technology has been widely used in wireless systems. However, the influence of mutual coupling among antennas in a wireless terminal is usually under estimated. In this paper, the impact of mutual coupling on data throughput is experimentally investigated. Two MIMO antennas with mutual coupling levels, ranging from -11 dB to -30 dB, are connected with an L TE module operating in band 3 as test beds and an anechoic chamber equipped with a 16-channel dual polarized multipath channel emulator is used for MIMO OTA measurement. Spatial Channel Model Extension (SCME) model is adopted in the OTA tests. The measurement results show that 1.8 dB power backoff can be achieved for mutual coupling being reduced from -11 dB to -30 dB and that a quasi-saturation point of mutual coupling for a pair of MIMO antennas is -20 dB.