In this study, we proposed an indoor broadband dual-polarized 2 × 2 MIMO (multiple-input and multiple-output) antenna having dimensions of 240 mm × 200 mm × 40 mm, for application in 5G wireless communication systems. The proposed antenna comprised two vertically polarized circular monopole antennas (CMAs), two horizontally polarized modified rectangular dipole antennas (MRDAs), and a ground plane. The distance between the two MRDAs (MRDA1 and MRDA2) was 70.5 mm and 109.5 mm in the horizontal (x-direction) and 109.5 mm vertical (y-direction) directions, respectively. Conversely, the distance between the two CMAs (CMA1 and CMA2) was 109.5 mm and 70.5 mm in the horizontal (x-direction) and vertical (y-direction) directions, respectively. While the CMAs achieved broadband characteristics owing to the optimal gap between the dielectric and the driven radiator using a parasitic element, the MRDAs achieved broadband owing to the optimal distance between the dipole antennas. The observations in this experiment confirmed that the proposed could operate in the 5G NR n46 (5.15–5.925 GHz), n47 (5.855–5.925 GHz), n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), and the n79 (4.4–5 GHz) bands. Moreover, it exhibited a wide impedance bandwidth (dB magnitude of ) of 101% in the 2.3–7 GHz frequency range, high isolation (dB magnitude of ), low envelope coefficient correlation (ECC), gain of over 5 dB, and average radiation efficiency of 87.19%, which verified its suitability for application in sub-6 GHz 5G wireless communication systems.
Requisite design area on the ground plane of U-shaped folded dipole antennas