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

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 withλ / 2metal 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 by 51.5 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.