A Novel DGS-Based Bandstop Filters Integrated Compact Four-Port MIMO Antenna for IEEE 802.11n/ac WLAN Standards

This work introduces a compact novel four-port Multiple-Input Multiple-Output structure with DGS-based decoupling elements for the 5.2GHz band of WLAN standards. The DGS decoupling elements are L-shaped open-ended slots etched on the ring-shaped common ground plane between the curve-shaped radiating elements. The optimized decoupling slots function as bandstop filters to suppress the surface current distribution through the common ground plane in the targeted 5.2 GHz band (5.15-5.35GHz) to enhance the isolation. The MIMO antenna achieves peal isolation of 23 and 26dB between adjacent and diagonal elements despite its compact footprint of $24\times 24$ mm2.