A Wideband Wide-Angle Beam Scanning Antenna for 5G Millimeter-Wave Applications

This paper presents the design of a four-element wideband antenna array for wide-angle beam scanning. Each array element operates within a 3 GHz bandwidth ranging from 24 to 27 GHz, corresponding to a relative bandwidth of 11.8 %. The array achieves beam scanning over a wide range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 50^{\circ}$</tex>, with the main beam gain reduction kept below 3 dB within the scanning range, and sidelobe levels maintained at less than -5 dB. The primary challenge lies in achieving a wideband antenna design capable of supporting a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 50^{\circ}$</tex> beam scanning range within the 3 GHz operating bandwidth. To address this, parasitic patches are incorporated to enhance the bandwidth of the antenna, reduce the element spacing, and subsequently lower sidelobe levels during beam scanning. Additionally, neutralization lines (NLs) are introduced to significantly reduce mutual coupling between the elements. With the implementation of NLs, the isolation between elements is improved from 9 dB to 14 dB, with the lowest value reaching 25 dB.