Intercoupling Suppression of Very Closely Spaced MIMO Antenna Based on Current Cancellation Method

Abstract

Herein, a high isolation multiple-input‑multiple-output (MIMO) antenna with a very close array element spacing, is proposed. By loading a pair of L-shaped parasitic stubs on the antenna feeder, the impedance matching bandwidth of the antenna is significantly improved. Furthermore, since the λ/2 microstrip line can make the signal through it produce 180°phase transformation at the resonant frequency. A dielectric wall decoupling structure with λ/2 metal microstrip lines etched on both sides of the substrate is designed, and its profile height is 1.3 mm ( 0.022λ0 ).When the antenna element edge-to-edge distance is only 1mm ( 0.017λ0 ), the isolation of the MIMO antenna at the resonant frequency of 5.37 GHz is improved from 8.5 dB to 60 dB by introducing the dielectric wall decoupling structure. Finally, the close-spacing MIMO antennas using current cancellation method are compared, and the results show that the proposed decoupling structure is simple and has great versatility and extensibility.