Quad Ports Millimeter‐Wave MIMO Antenna With Parasitic Element and Defected Ground Structure for Radar Sensing Application

Abstract This paper presents a quad‐element MIMO antenna with a novel decoupling structure for mm‐wave 5G radar sensing applications. The proposed MIMO antenna is fabricated on Rogers RT/5880, which is suitable for high frequency communication. Furthermore, effective techniques for novel parasitic elements and a defected ground structure (DGS) are introduced to minimize inter‐element coupling in the required bandwidth. The parasitic element consists of a square ring and a four‐line parasitic. The ring parasitic is rotated 45° anti‐clockwise and line parasitic elements are rotated 5° from the original position to obtain the proposed design. The line parasitic elements coupled from adjacent elements and square ring parasitic neutralize current. The DGS is introduced to enhance isolation further. The slot is inserted in the center of the ground plane. Two rectangular slots are also inserted to isolate adjacent elements. The edge‐to‐edge space between the radiation elements is 5.6 mm. The antenna exhibits S11 of <−10 dB from 23.5 to 28 GHz, with an impedance bandwidth of 4.5 GHz and mutual coupling of <−27 dB within the given bandwidth. The peak gain of the proposed antenna is 8.42 dBi. The envelope correlation coefficient (ECC) is <0.001, diversity gain (DG) is >9.99 dB and multiplexing efficiency is −0.5 dB within the given bandwidth. The multiplexing efficiency, radiation pattern, ECC, DG, and peak gain are also calculated and evaluated for practical authentication.