A Dual-Band Frequency Reconfigurable MIMO Patch-Slot Antenna Based on Reconfigurable Microstrip Feedline

In this paper, a novel microstrip feedline-based dual-band frequency reconfigurable multiple-input multiple-output (MIMO) patch-slot antenna design is presented. The antenna has a planar structure and comprises four symmetrically placed rectangular patch antenna elements. A dual-purpose hexagonal-shaped defected ground structure (DGS) is introduced into the ground plane for antenna size reduction and isolation enhancement. The overall size of the antenna is compact with total substrate area of $120\times 60\times1.6$ mm3 and is printed on FR4 substrate. Varactor diodes are integrated within feedline to achieve frequency reconfigurability. The proposed antenna design exhibits a wide continuous dual frequency reconfigurable characteristic from 1.3 to 2.6 GHz with isolation of more than 12 dB for entire band. The proposed design is verified by presenting the simulation and measured results of S-parameters, radiation pattern, efficiency, and envelope correlation coefficient (ECC), and displaying good agreement. ECC of less than 0.2 between the ports is achieved. The compact size and dual-band frequency reconfigurable characteristics make the proposed design potential candidate for wireless handheld devices and other multiband MIMO applications.