A wideband circularly polarized phased array antenna based on liquid crystal phase shifter technology

Abstract This paper presents an 8 × 8 wideband circularly polarized liquid crystal (LC) phased array antenna operating at 19.2 GHz. The design introduces a novel circularly polarized unit cell that combines a LC delay line-based phase shifter and radiator, incorporating dual fan-shaped elements for radio frequency isolation. Sequential rotation techniques are utilized to expand the unit cell into a 2 × 2 subarray, thereby enhancing the circular polarization performance. A hybrid waveguide-microstrip power divider network is employed to minimize feed loss and provide mechanical support. Furthermore, calibration ports are incorporated, allowing for direct measurement of the phase shift-bias voltage relationship in the LC phase shifter. By calculating the initial phase, rotation phase, and scanning phase, the applied phase is determined, enabling precise beam steering. The antenna array achieves a continuous scanning range of ±30° in elevation and 360° in azimuth. Experimental results show a broadside gain of 16.9 dBic and a 3 dB axial ratio bandwidth of 4.17% (0.8 GHz). The proposed antenna architecture holds great promise for applications in satellite communications, 5 G/6 G wireless systems, and compact radar platforms where broadband circular polarization and dynamic beam steering are required.