Experimental Evaluation of the Tri-Polarized MIMO Channel Properties Based on a Compact Multimode Antenna

Based on a planar and compact antenna, extensive measurements are conducted to investigate the behavior of the colocated tri-polarized multiple-input multiple-output (MIMO) system working at 3.5 GHz. Several scenarios with different multipath distributions have been considered, including a reverberation chamber (RC) and also some line-of-sight (LOS) and obstructed LOS (OLOS) real-world indoor environments. Many channel parameters of the MIMO system are analyzed based on the measured data, including cross-polarization discrimination (XPD), Ricean K-factor, correlation coefficient (CC), MIMO channel capacity gain (CG), channel eigenvalues, and ellipticity statistic (ES). The results show that for a multi-polarized MIMO system, the effects of polarization coupling and transition depend strongly on the polarimetric scattering characteristic of the environments. Furthermore, in all the scenarios tested, three non-zero eigenvalues of the MIMO channel matrix are obtained, which indicates that three independent subchannels can be supported by the tri-polarized MIMO system.