  This manuscript presents an ultra-wideband Microstrip
multiple-input-multiple-output (MIMO) antenna covering the 2.4GHz to 6.5 GHz
wireless local networks (WLAN) and Sub-6G bands. The applied MIMO antenna is
composed of two symmetrical microstrip antenna elements. Each microstrip is
designed based on the stepped impedance resonator (SIR) technique and closely
positioned with about 0.25lambda of the lower band (2.5 GHz). The proposed MIMO
antenna is incorporated with the EBG structure to enhance the radiation
characteristic and isolation between two radiating components. The return loss
(S11 under -10) covers 2.4 GHz to 6.5 GHz, and the proposed configuration
obtains about 20 dB isolation within the 2.4 GHz to 6.5 GHz Sub-6G and WLAN
bands, which shows an improvement compared to the initial design of the MIMO
antenna. The envelope correlation coefficient (ECC) is under 0.02 over the
frequency band. The simulation results offer that the proposed microstrip MIMO
antenna system with the different levels of the EBG structure is suitable for
WLAN and Sub-6G applications.
