Reducing Correlation in Compact Arrays by Adjusting Near-Field Phase Distribution for MIMO Applications

This paper presents a novel method of improving the correlation performance in a compact multiple-input multiple-output (MIMO) array. Unlike the previous work, the proposed method focuses on each antenna phase distribution in the array and reduces the correlation by adjusting the near-field phase distribution using phase correcting elements (PCEs). The PCEs provide the required transmission phase to modify the near-field phase distribution in a specific plane. Diversity measure and channel capacity are introduced as metrics to evaluate the MIMO system's array performances. The significance of the phase pattern on the correlation performance is investigated and demonstrated by comparing and analyzing four specially designed arrays' results. A 1 × 4 dual-polarized patch array with four PCEs is simulated, fabricated, and measured to verify the method. The diversity measure and channel capacity are improved by 0.5 (10%), 5 bit/s/Hz (12.2%), respectively, at 2.6 GHz when the channel's angular spread is 90°.