A Single-Layer Quad-Polarized 1-D Beam-Scanning Phased Array Antenna

This paper presents a single-layer low-profile 8×8 phased array antenna with quad-polarization switching and 1-D beam scanning capability. By controlling the excitation phases of 16 ports, the array achieves switching between left-hand/right-hand circular polarizations and horizontal/ vertical linear polarizations, while realizing ±30° scanning in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz-plane</i>. The dual-end feeding configuration of the series-fed array ensures frequency-stable beam pointing along the y-axis direction. Through vector projection analysis, the equivalent phase center spacing between two radiating fields when exciting both ports is identified as the key factor affecting cross-polarization levels during polarization synthesis in the upper hemisphere. A 1-to-8 equal-power divider and sequentially rotated minimum periodic subarray are implemented to suppress cross-polarization across the upper hemisphere. The fabricated array, printed on a 0.635 mm (0.0123λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">₀</sub>, where λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">₀</sub> is the free-space wavelength at 5.8 GHz) substrate, achieves an active VSWR below 2.2 during ±30° beam scanning for all four polarization modes, while maintaining operation within the 5.75-5.85 GHz band. Simulation and measurement results show good agreement.