A Four‐Port Wideband High‐Isolated Slot MIMO Antenna Based on Self‐Decoupling Technology and DGS

ABSTRACT In this letter, a four‐port self‐decoupling wideband slot multiple‐input‐multiple‐output (MIMO) antenna is presented, where the principle of current cancellation and defect ground structures (DGS) are utilized to realize high isolation. In particular, a four‐port wideband slot MIMO antenna is designed with an element spacing of 0.16 λ at the center operating frequency. It is formed by rotating a basic slot antenna counterclockwise by 90°, 180°, and 270°, respectively. Initially, decoupling is achieved based on the principle that the currents have the same amplitude but opposite phases. In the sequel, a rectangular ring and a cross‐shaped structure are loaded in the center of the four slot elements to further enhance the isolation of the four‐port MIMO antenna. A prototype is fabricated and measured. The simulated and measured results show that the proposed antenna achieves an isolation of better than 23 dB and operates at 3.62–6.00 GHz, which can cover three frequency bands of n77 (3.7–4.2 GHz), n79 (4.4–5.0 GHz), and n256 (5.0–5.9 GHz). Moreover, it exhibits low correlation coefficient (< 0.002), stable gain, and excellent total efficiency (> 80%). It should be emphasized that all the radiation patterns presented in this letter have been virtually undistorted, which is beneficial for practical applications utilizing MIMO technology.