Shared-Aperture Phased Array Antenna With Codesigned Near-Field Coupled Circular Polarizer Loaded for K/Ka-Band Wide-Angle Satellite Communication

Abstract

A K-/Ka-band shared-aperture linear polarization (LP) phased array antenna and a circular polarizer are combined to realize circular polarization (CP) beam scanning. When the polarizer is close to the antenna array, its performance will become difficult to predict due to the influence of the antenna source. This will bring uncertainty to the cooperative work. We propose a codesign method of polarizer unit considering the factor of antenna array. This method can better design the polarizer working in the near field of antenna array. Next, to improve the CP scanning range, the polarizer is not composed of repeated units, but adopts a codesign partition scheme. We combine the polarizer unit specially designed for large-angle incidence and for normal incidence to a polarizer plane. The partition scheme is optimized with an algorithm according to the field distribution of antenna. This combination produces right-hand circular polarization (RHCP) at 19.7–20.2 GHz and left-hand circular polarization (LHCP) at 29.5–30 GHz, and the axial ratio (AR) of CP is less than 4 dB in the scanning range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 55^{\mathrm {\circ }}/\pm 60^{\mathrm {\circ }}$ </tex-math></inline-formula> at two operating bands. The proposed combination concept and the design results have been validated by the experimental results.