Mutual Coupling Suppression in Antenna Arrays Using Meandered Open Stub Filtering Technique

Abstract

Multiple-input and multiple-output (MIMO) systems utilize multiple antenna elements to improve channel capacity and achieve higher data rates. The successful implementation of MIMO systems requires low mutual coupling between antenna elements to reduce the envelope correlation coefficient (ECC) at the operating frequency. In this paper, we introduce a mutual coupling suppression technique using an open stub meandered (OSM) bandstop filter (BSF) design for MIMO applications. The OSM-BSF is optimized and implemented on the ground plane side of a two-element patch array. The designed filter provides high isolation of 60 dB at 2.4 GHz across a 30% bandwidth. A parametric study of antenna element spacing was carried out, showing at least 40 dB of mutual coupling suppression in the antenna array, irrespective of the antenna element spacing. A two-element antenna array prototype with OSM-BSF was fabricated and tested. Measurements showed that ≥ 57 dB isolation was achieved using OSM-BSF. Besides, the fabricated array provides a low ECC of 0.0093 at 2.42 GHz, while maintaining edge-to-edge spacing as little as 0.19λ0.