A Method to Design Compact MIMO Patch Antenna Using Self-Isolated Technique

This paper presents a method to design a compact high-gain multiple-input, multiple-output (MIMO) patch antenna. In a one-dimensional large-scale MIMO array, the conventional approach of using multiple patches and decoupling networks significantly increases the antenna size. To address this, this paper utilizes compact self-decoupled patches, enabling extremely small element spacing while maintaining high isolation levels. Accordingly, a compact size feature can be obtained. Then, gain and bandwidth enhancements are realized with a combination of multiple patches and T-junction dividers. The feasibility of the proposed concept is validated by measurement on a two-element MIMO antenna. The measured results demonstrate that the proposed antennas have good operation characteristics at 4.8 GHz with a small element spacing of 0.008λ. The measured operating bandwidth is about 5%, with isolation of better than 19 dB. A maximum broadside gain of 7.2 dBi can also be yielded.