Ultra-wideband linear-to-circular polarization converter with ellipse-shaped metasurfaces

Generally, a traditional method to generate circularly polarized waves faces limitations like the narrow band, bulky volume and low efficiency. In this paper, a linear-to-circular (LTC) polarization converter based on metasurface with high efficiency and maneuverable ultra-wideband is proposed. By utilizing the ellipse-shaped structure on reflective metasurface, the LTC polarization converting condition can be achieved at four closer frequencies, leading to a quite wide frequency band. The simulated results show that the axial ratio of the reflective circularly polarized wave is lower than 3 dB within the frequency band of 10.21-24.97 GHz, and a relative band reaches above 83.91%. Furthermore, the bandwidth of the polarization conversion can be sustained from 10.21 to 22.71 GHz at incident an angle of 48 degrees. The electrical field and current flows are given to analyze the circular polarization performance. For validation, a sample is fabricated and measured; measured results and simulated results coincide with each other. The proposed LTC polarization converter is easy in terms of design and fabrication complexity, showing promising potentials in real-world circularly polarized wave generator applications.