Single-Layer Dual-Band Linear-to-Circular Polarization Converter With Wide Axial Ratio Bandwidth and Different Polarization Modes

Abstract

A dual-band linear-to-circular polarization converter (LCPC) based on a single-layer dielectric substrate is proposed. The element of the converter consists of two identical metallic layers with a combination of a connected Jerusalem cross (JC) and an “I”-type dipole for each layer. The proposed converter is designed by using an equivalent circuit model (ECM). Left-handed circularly polarized (LHCP) and right-handed circularly polarized (RHCP) beams can be, respectively, generated at ${K}$ -band and Ka -band excited by a linearly polarized (LP) wave tilted 45° relative to the ${x}$ - and ${y}$ -directions of the converter. In addition, the converter covers two operation bands for ${K}$ -/ Ka -band satellite communications with high conversion efficiency and low polarization extinction ratio (PER). After full-wave optimization, the proposed converter is fabricated and measured. The measured results show a good agreement with the simulated ones. Even though there exists a tradeoff between the angular stability and the bandwidth of the dual-band LCPCs, the measured axial ratio (AR) remains stable in the lower operation band and a slight fluctuation in the higher band with the incident angle of 20°.