Dual-band four-element MIMO antenna array for 5G millimeter-wave communication

This paper presents a four-element dual-band multiple-input-multiple-output (MIMO) antenna array designed to operate in 5G millimeter-wave (mm-wave) spectrum. The designed antenna system is configured using four 1 × 4 antenna subarrays. An antiparallel arrangement is used for the unit element subarrays (UESAs) to enhance isolation and improve radiation performance. The UESA consists of four identical symmetrically arranged modified rectangular patches and T-junction power dividers. This feeding configuration ensures equal power division, maintains phase coherence, and provides stable excitation to the radiating elements. The proposed MIMO antenna array occupies an overall volume of 40 mm × 96 mm × 0.254 mm and operates over the frequency ranges of 28.3–29.1 GHz (FBW ≈ 2.8%) and 38.31–39.13 GHz (FBW ≈ 2.1%). High inter-port isolation is achieved, exceeding 25 dB and 30 dB across the lower and upper operating bands, respectively. The designed MIMO antenna array achieves peak realized gains of 9.1 dBi and 12.4 dBi at 28.7 GHz and 38.72 GHz, respectively. The excellent radiation characteristics, combined with enhanced MIMO performance, establish the proposed antenna system as a promising candidate for mm-wave 5G applications.