Compact dual‐mode wideband MIMO filtering antenna array with high selectivity and improved isolation

Abstract

A novel compact MIMO dual-mode filtering antenna array with wide bandwidth, high selectivity and good isolation is proposed. The filtering antenna unit consists of a patch radiator at the top layer coupled with a high-order dual-mode filter at the bottom layer through a rectangular slot in the middle ground layer. The fourth-order filter adopts two E-shape dual-mode resonators to achieve wide bandwidth and high selectivity. A pair of filtering antenna units form a MIMO array with a distance of 0.2λg by using three interdigital lines in the middle to enhance the port isolation. Finally, a 1 × 2 MIMO filtering antenna array operating at 2.45 GHz is designed and fabricated, which shows wide fractional bandwidth of 24.5%, sharp skirt slope with a pair of radiation nulls, smooth realized gain of 4.5 dBi as well as high isolation more than 20 dB.