A Compact Decoupling Structure Applied in MIMO Antennas for Wideband Radar Applications

In this paper, a novel decoupling structure is proposed to depress mutual coupling among closed-spaced elements in MIMO antenna design for the distance of 0.1457λ. The proposed structure, based on gradient line, has reduced mutual coupling in a wide range of frequency, for over 800MHz around 9.5GHz. The structure was analyzed using equivalent circuit and applied in MIMO and array antenna designs to reduce mutual coupling and distortion of radiation pattern. The measured results were also presented and agree well with simulated ones.