Triple-Band Notched and Highly Decoupled MIMO Antenna Using Characteristic Mode Analysis

This study presents a decoupled four-port multiple input multiple output (MIMO) antenna with three notched bands, which is systematically designed using characteristic mode analysis (CMA). A modified rectangular-shaped radiator with a ground plane integrated with a small open-ended slot is conceptualized as a quasi-monopole ultra-wideband (UWB) antenna with compact dimensions of 24 mm <inline-formula> <tex-math notation="LaTeX">$\times 17$ </tex-math></inline-formula> mm. The ultra-wide range is achieved using exciting wideband modes where modal significance <inline-formula> <tex-math notation="LaTeX">$\boldsymbol {\ge }~0.8$ </tex-math></inline-formula>. The three notched bands (NBs) are designed by introducing various slots in the radiator, which produce radiation-cancelling modes with opposite current directions at the corresponding slots. Then, a four-element MIMO antenna is created by arranging each antenna element (AE) in an orthogonal configuration. The multiply-shaped structure, combined with a square ring, provides orthogonal modes for high isolation between AEs. The MIMO antenna construction achieves <inline-formula> <tex-math notation="LaTeX">$2-16.49$ </tex-math></inline-formula> GHz bandwidth, 6.72 dB peak gain, and more than 75% radiation efficiency with &#x003E;16 dB isolation between the AEs. Diversity performances are observed to be within adequate limits.