摘要： In this letter, a novel polarization conversion (PC) structure is introduced, and its use with a wideband, wide 3-dB axial-ratio (AR) beam, low-radar-cross-section (RCS) circular polarization (CP) slot antenna is suggested. The unit cell of the proposed PC metasurface (PCM) consists of square and L-shaped patches separated by an L-shaped slot printed on an FR4 substrate. The mechanisms for linear to circular polarization and bandwidth improvement of a conventional antenna are analyzed theoretically. Through numerical optimizations and parametric studies, a simulated 10-dB impedance bandwidth of 42.7% (4.15-6.4 GHz) and a 3-dB AR bandwidth of 26.2% (4.8-6.25 GHz) are achieved by the proposed antenna. As the simulation demonstrates, the proposed antenna achieves an average 20-dB RCS reduction in a wide band from 5.25 to 6.8 GHz compared to a conventional slot antenna covered by the PC band. In addition, compared to previously reported work, the PCM-based CP antenna exhibits a larger 3-dB AR beam width of 200° in the xoz plane and 120° in the yoz plane, and a wider CP bandwidth within the operational bandwidth. Finally, an overall volume of 0.55λ0×0.55λ0×0.05λ0 centered at 5.275 GHz is fabricated and measured, demonstrating good agreement with the simulation results.