A Compact Eighth-Mode Circular SIW Cavity-Based MIMO Antenna

A verycompact and simple two-port multiple-input-multiple-output (MIMO) antenna is presented in this letter. The antenna element is designed based on the 1/8th mode modified circular substrate integrated waveguide cavity. The proposed MIMO antenna offers a bandwidth of 3.43% and resonates at 3.5 GHz. The isolation network consists of a single narrow linear half-wavelength slot and it offers a minimum isolation of 30 dB over the operating band. With a smaller physical area of 40 × 40 mm
²
, the proposed compact antenna offers a significant gain of 4.03 dBi. The envelope correlation coefficient values over the operational bandwidth are well within the accepted threshold limit. The proposed antenna is well suited for 5G wireless communication system applications. The design concept is further extended to a compact four-port MIMO antenna.