A Dual-Polarization Beam-Scanning Antenna Array with Feeding Network for 5G N41 Band

This paper proposes a dual-polarized <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4 \times 1$</tex> beamscanning antenna array operating in the 5 G NR n41 band. The antenna array can be interfaced with two RF chains, four elements, and a feeding network to achieve equal amplitude excitation. We introduce an aperture-coupled microstrip patch antenna structure, where two orthogonal slots are used to excite the orthogonal polarization modes, and we conduct a mode analysis of the antenna's radiation patterns. Beam-scanning is achieved using integrated phase shifters to control each element's input phase. The designed antenna array has a compact size of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2.05 \lambda_{0} \times 0.5 \lambda_{0} \times 0.12 \lambda_{0}$</tex>, and due to the use of FR4 substrate, the prototype offers low manufacturing costs. In measurements, both <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm \text{4 5}^{\circ}$</tex> polarization modes cover the bandwidth from 2.5 to 2.67 GHz, with isolation between the two RF chains remaining below -30 dB within the band. Regarding radiation performance, the antenna array achieves a normalized gain of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{1 0 ~ d B i}$</tex> and a cross-polarization suppression of -15 dB. The beam-scanning ability of the antenna array is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{- 4 5}^{\circ}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{+ 4 5}^{\circ}$</tex> using a microstrip phase shifter circuit. Within the range from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-30^{\circ}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$+30^{\circ}$</tex>, it achieves a low sidelobe level (SLL) lower than -10 dB.