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

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 <inline-formula> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula>-band and <italic>Ka</italic>-band excited by a linearly polarized (LP) wave tilted 45° relative to the <inline-formula> <tex-math notation="LaTeX">${x}$ </tex-math></inline-formula>- and <inline-formula> <tex-math notation="LaTeX">${y}$ </tex-math></inline-formula>-directions of the converter. In addition, the converter covers two operation bands for <inline-formula> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula>-/<italic>Ka</italic>-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°.