A Low-Profile 1-bit Electronically Controlled 2-D Beam-Scanning Millimeter-Wave Circularly Polarized Antenna With Wide-Angle Axial Ratio

This paper presents a novel low cost, low-profile, wide-angle axial ratio, electronically controlled two-dimensional beam-scanning circularly polarized millimeter-wave antenna array. The antenna comprises Rogers RO5880 and Rogers RO4350B substrates. The Rogers RO4350B substrate ensures the mechanical robustness of the antenna array, while the lower-loss Rogers RO5880 substrate is utilized to minimize transmission loss. A reflective phase shifter loaded with two diodes is used to provide 0°/180° phase switching, and a mushroom-shaped electromagnetic bandgap structure is integrated beneath the phase shifter to suppress power leakage. A double-layer stacked patch structure is adopted for the circularly polarized element to broaden its bandwidth, while sequential rotation technique is implemented in the array to extend the beam scanning range with axial ratio < 3dB. Furthermore, the capability of the sequential rotation technique to suppress parasitic beams in 1-bit circularly polarized arrays is analyzed. Subsequently, a method of reducing antenna sidelobe levels is developed, which loads specific phase delays onto the antenna and optimizes them using genetic algorithm. Finally, an 8×8 prototype is fabricated and measured, achieving an axial ratio below 3dB over a ±50° beam-scanning range and a peak gain of 16.9dBic from 23 to 26 GHz. This design demonstrates promising application prospects for future wireless communication systems.