A Microstrip-Line Fed Quad-Port MIMO Antenna with Defected Ground Structures for Wireless Applications

A microstrip line fed quad-port MIMO (Multiple Input Multiple Output) antenna with defected ground structure is discussed for wireless applications. The prototype of the MIMO antenna consists of four identical rectangular microstrip antenna elements extended towards each other and printed on 1.6 mm thick FR-4 substrate with an overall dimension of 62.8X60 mm2. The proposed MIMO antenna elements are etched out with multiple rectangular edge slits from the top of the metallic surface and ground plane defected with octagon split-ring slot defected ground structure (OSRSDGS) periodically to obtain wideband operation of the antenna. The proposed MIMO antenna is resonating at the frequency 4.1GHz and 5.9GHz with a bandwidth of 98MHz and 475MHz, respectively, which makes it suitable to use for wireless applications. The MIMO antenna has achieved mutual coupling less than -33.4dB in the lower band and less than -25.6dB in the upper band. The measured and simulated results show good agreement in both the bands. Moreover, the MIMO antenna parameter such as data rate, envelope correlation coefficients (ECC), and diversity gain (DG) performance have also been analyzed.