A Wideband Hybrid Decoupling Scheme Using Absorbing Structures and Periodic Surfaces for MIMO Antenna Arrays

This letter presents a hybrid decoupling method for compact wideband MIMO antenna arrays, where absorptive structures (ASs) and array decoupling surface (ADS) are jointly employed. In this method, ASs are vertically placed around the antenna elements to suppress near-field coupling and establish a relatively uniform electromagnetic boundary that enhances radiation pattern consistency among antenna elements. Subsequently, an ADS is integrated as a director to further strengthen radiation uniformity and improve the overall efficiency of the subarrays. Simulated and measured results verify that the array maintains wideband isolation across 1.7-2.7 GHz (45.5%, VSWR < 2), with mutual coupling reduced below - 20 dB. Additionally, the gain variation between subarrays remains within 0.7 dB, and the half-power beamwidth fluctuation is less than 20° in the horizontal plane and 1° in the vertical plane, demonstrating the strong potential of the proposed method for application in MIMO antenna systems with compact layout.