A Compact “Frequency Selective Surface‐MIMO Antenna‐Metasurface” composite structure for 24–32 GHz 5G FR2 Applications

ABSTRACT A novel three‐layered compact high‐gain wideband MIMO antenna with electromagnetic (EM) shielding is proposed and analyzed. The design integrates a millimeter‐wave 4 × 4 MIMO antenna of 22 × 22 × 0.5 mm, a metasurface for radiation enhancement with unit cell dimension of 4 × 4 × 0.3 mm, and a frequency selective surface (FSS) with unit cell dimension of 4.6 × 4.6 × 0.5 mm for EM shielding, forming a unique composite structure. The MIMO antenna operates over a wideband spectrum of 23.7–40 GHz, achieving a fractional bandwidth of 51%, but exhibits a low inherent gain. To address this, a metasurface with multi‐stopband characteristics is placed beneath the antenna, improving gain and radiation in the broadside direction. Additionally, an FSS superstrate with a wide passband enhances spectrum selectivity and suppresses out‐of‐band interference, specifically targeting 5G FR2 spectrums, including n‐257, n‐258, and n‐261 bands. The combined “FSS‐MIMO antenna‐metasurface” covers 24.15–31.86 GHz 5G FR‐2 spectrum with highest gain 11.64 dBi, efficiency 78%, and satisfactory ECC (< 0.005), DG (> 9.99 dB), MEG (between −3 and −11 dB), CCL (< 0.4bits/s/Hz), and TARC (≤ −10 dB) characteristics. The proposed design is compact and optimized for 5G and beyond wireless technologies, which is a combination of three distinct structures (FSS‐MIMO antenna‐metasurface) to form a novel three‐layered antenna module. Tactical fixation of three‐layered antenna module inside a mobile phone optimizes space utilization in modern smartphone handsets.