Capacity and spatial correlation measurements of compact MIMO antennas

Abstract

The dual-port compact multiple-input multiple-output (MIMO) dipole antennas with close spacing d of 0.5 λ and 0.3 λ are designed, and some electromagnetic band gap (EBG) structures are inserted between them to reduce mutual coupling. Those MIMO antennas with d = 0.5 λ and 0.3 λ, and with different mutual couplings are fabricated and measured, the channel capacity and correlation coefficient (CC) are analyzed and compared in a rich multipath reverberation chamber (RC), an office and a conference room. Results show that if d is reduced from 0.5 λ to 0.3 λ, in the RCs, channel capacities of all the antennas are very close to that of the i.i.d. Rayleigh channel, although the average CCs are increased from 0.168 in the nonlossy RC to 0.269 in the lossy RC. In the office and conference rooms, compared with the RC, the average capacities of those antennas get a slight reduction, however, in most cases, the capacity of d = 0.5 λ is larger than that of d = 0.3 λ, and the antennas with EBG have a larger capacity compared with the antennas without EBG, with a corresponding reduction of CC. A non-line-of-sight (NLOS) scenario of through-the-wall is also investigated.