volume | PIER Journals

Abstract

This paper presents a novel key-shaped miniaturized four-port MIMO antenna designed for ultra-wideband (UWB) applications. The proposed antenna consists of four orthogonally and symmetrically arranged key-shaped radiating elements. By integrating semi-circular patches at the edges of rectangular radiators, multiple resonance modes are excited to significantly broaden the impedance bandwidth and optimize matching. To suppress mutual coupling within a compact footprint, an enhanced cross-shaped defected ground structure (DGS) is implemented, which effectively blocks surface wave propagation by utilizing narrow rectangular stubs. Experimental results demonstrate that the antenna achieves a continuous impedance bandwidth from 4.4 to 26 GHz, corresponding to a fractional bandwidth of 141.5%. Throughout the operating band, the port isolation remains better than 28 dB, while the envelope correlation coefficient (ECC) is lower than 0.00013, ensuring excellent diversity performance. Furthermore, the antenna, fabricated on an FR4 substrate with a compact size of 47 × 47 × 1.6 mm³, maintains a radiation efficiency between 67.4% and 92.6%. With its superior bandwidth, high isolation, and exceptionally low correlation, the proposed design offers a robust solution for high-performance UWB communication systems.

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Mr. Xinyu Liu

Professor Han Lin

Professor Zhonggen Wang