Isolation Enhancement in Millimeter-wave MIMO Array Base on Array-Antenna Decoupling Surface

Abstract

A new array-antenna decoupling surface (ADS) is designed in this paper to enhance port isolation of the millimeter-wave(mm-wave) MIMO array. First, a novel ADS element is designed by combining a square loop and a cross-shaped strip. Then, an array decoupling surface is designed based on the novel ADS element. In order to verify the decoupling effect of the proposed ADS, a two-element millimeter-wave patch array is designed with a small element spacing of 3.8 mm (0.329λ0, where λ0 represents the wavelength at the center frequency). After stacking the proposed ADS above the array, the port isolation is significantly increased from 11.7dB to 44dB at 24.9GHz, from 11.9 dB to 53.8 dB at 26.5 GHz and keeps larger than 25 dB in the operating band of 24.24-27.44 GHz. The good decoupling effect make the proposed ADS very suited for millimeter-wave MIMO system.