Mutual Coupling Reduction in Dual-Band MIMO Antenna Using Parasitic Dollar-Shaped Structure for Modern Wireless Communication

Abstract

A dual-band Multiple Input Multiple Output (MIMO) antenna with low mutual coupling is analyzed and studied for Fifth Generation (5G) Sub-6 GHz and Wireless Fidelity (Wi-Fi) 6E frequency-band applications. Each of the identical monopole radiators consists of a rectangular patch, inverted-E, and asymmetrical T-shaped strip to generate 5G Sub-6 GHz and Wi-Fi 6E frequency bands. The deployment of the radiators horizontally with end-to-end separation of 5mm makes the antenna compact with an overall dimension of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$45\times 30$ </tex-math></inline-formula> mm2 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.37\lambda \times 0.25\lambda $ </tex-math></inline-formula> for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> at the lower resonating frequency of 2.5GHz). The antenna achieves measured impedance bandwidths of 2.39-2.57 GHz and 3.82-6.95 GHz, respectively, at two resonating frequencies of 2.5 GHz and 4.5 GHz. A Parasitic Dollar Shaped Structure (PDSS) introduced between the two monopole radiators to suppress the surface waves of each monopole reduces the measured mutual coupling up to -15 dB throughout the operating band. Furthermore, the measured gain, radiation efficiency, Envelope Correlation Coefficient (ECC), and Diversity Gain (DG) values remain in good agreement with simulated values and are well within the minimum limit set by industry standards. These results affirm the applicability of the MIMO antenna for 5G and Wi-Fi 6E frequency bands.