In this paper, a wideband and wide-angle transmissive linear-to-circular polarization converter (LCPC) working in the C, X and Ku bands is proposed, which is based on a single-layer dielectric substrate. In order to increase the axial ratio bandwidth of the single-layer LCPC, a method of combining infinite length metal strips and horizontal strips is proposed, which cannot only improve the passband, but also realize large phase difference conversion. The single-layer LCPC with small size is designed and optimized, which can maintain axial ratio stability in the ultra-wide band over large incident angles. When the linear polarized (LP) wave is normal incident, the 3 dB axis ratio bandwidth of LCPC is 6.41–15.07 GHz (relative bandwidth 80.63%). When LP wave oblique incident along the yoz plane, the axial ratio bandwidth will increase with the increase of the incident angle, it is worth noting that when the incident angle reaches 45°, its 3 dB axial ratio bandwidth can reach 100.6%. Moreover, when LP wave oblique incident along the xoz plane, the insertion loss is always less than 3 dB within the working bandwidth, and the incident angle can even reach more than 70°. The measured results are in good agreement with the simulated ones. The LCPC can be widely used in multi-beam antenna, beam scanning antenna and satellite communication. [ABSTRACT FROM AUTHOR]