Quad-port planar MIMO antenna with wideband capabilities for millimeter-wave 5G Ka-band applications

Abstract A Quad-port multiple-input multiple-output (MIMO) antenna design with enhanced isolation using defected ground structure (DGS) techniques has been presented. The antenna operates in the millimeter-wave (mm-wave) frequency ranges of 27–40 GHz, specifically for Ka-band applications. The antenna consists of four rectangular radiating elements with diamond-shaped slots on top and a DGS at the bottom, all mounted on a 22 × 22 mm 2 Rogers RT/Duroid5880 substrate. Incorporating DGS-based slots in the ground plane improves the isolation between antenna ports by 19 dB. To validate the design in a real-world scenario, the antenna is fabricated and its performance is evaluated. The design achieves a 10 dB impedance bandwidth and over 19 dB isolation across the entire operational spectrum. The radiation patterns, gain, efficiency, and current distribution are analyzed, along with diversity characteristics such as Diversity Gain (DG) and Envelope Correlation Coefficient (ECC). The proposed antenna operates in the mm-wave frequency range, making it suitable for the high data rate and low latency requirements of Ka-band applications. The design focuses on achieving wideband performance, high isolation, and stable gain, essential for reliable Ka-band communication.