A Four-Element MIMO Loop-Shaped Slot Antenna Array for Access Points Applications

A novel four-element multiple-input multiple-output (MIMO) loop-shaped slot antenna array for Wireless Fidelity (WiFi) access points is proposed. The four loop-shaped slot antennas were etched on a four-port square patch antenna. This antenna excites two operating modes, which are a slot mode and a patch mode. The dimensions of the MIMO antenna array are 62 × 62 × 9 mm^3 (1.06λ0 × 1.06λ0 × 0.15λ0, at the 5.15 GHz). Shorting pins were added to reduce the mutual coupling and to support the square radiating patch. The measured 10-dB impedance bandwidth is from 5.15 to 7.13 GHz, the measured total efficiency is 56–97%, and the measured peak gain is 1.5–8.1 dBi. The transmission coefficient is less than -17 dB, the envelope correlation coefficient (ECC) is less than 0.015, and the channel capacity (CC) is 21.15–21.82 bps/Hz.