volume | PIER Journals

Abstract

In this paper, a racket-shaped ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna is analytically designed using characteristic mode analysis. The antenna has an overall size of 60 × 60 × 1.6 mm³ and consists of four racket-type radiating elements, four ground planes shaped like the number 6, and a cross-shaped decoupling structure between the radiating units. In the single antenna configuration, the feed position is determined by analyzing the current and electric field distributions of its characteristic modes. The bandwidth and current distribution are optimized by integrating seven small rings, L-shaped branches, and etched slots to ensure the simultaneous excitation of six characteristic modes, thereby enabling its UWB performance. In the MIMO setup, four elements are orthogonally arranged, and a cross-shaped decoupling structure along with a defected ground structure is employed to reduce mutual coupling, achieving over 20 dB isolation between any two elements. Simulated and measured results confirm that the antenna operates over the 3-21 GHz range, fully encompassing the UWB range of 3.1-10.6 GHz. Furthermore, the antenna achieves up to 77% radiation efficiency, a peak gain of 5.75 dBi, and a low envelope correlation coefficient (ECC).

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doi:10.2528/PIERM24011101

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Professor Zhonggen Wang

Dr. Fukuan Zhang

Professor Wenyan Nie

Dr. Ming Yang

Dr. Chenlu Li