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In this work, an anisotropic metasurface is proposed for linear-to-circular (LTC) and circular-to-linear (CTL) polarization conversions, which is composed of a square array of two-corner-cut square patches printed on a grounded dielectric substrate and covered by a dielectric layer. Numerical simulation results show that the anisotropic metasurface can act as a high-efficiency ultra-wideband reflective polarization converter to achieve both LTC and CTL polarization conversions. Under x- and y-polarized incidences, its reflected wave will be converted to left-handed and right-handed circular-polarized (CP) waves, respectively, in the ultra-wide frequency band between 7.14 and 25.66 GHz with a relative bandwidth of 113%, and the polarization conversion ratio (PCR) can be kept larger than 99.73% in the frequency range of 7.72–25.08 GHz; in addition, the reflected wave under CP incidence will be converted to an x- or y-polarized wave, and the bandwidth and PCR of the CTL polarization conversion are almost the same as those of the LTC polarization conversion. Finally, the working principle of the polarization converter is illustrated, moreover, an effective experimental verification is carried out, and a reasonable agreement is observed between the simulation and experimental results. [ABSTRACT FROM AUTHOR]

In this work, one 8-shaped metasurface (MS) is proposed, which consists of a square array of 8-shaped conducting patches printed on a grounded dielectric substrate and covered by a top dielectric layer. Because the MS is symmetric with respect to both the x- and y-axes, and the phase difference between the reflection coefficients rxx and ryy is close to + 90° in an ultra-wide frequency band, it can be used as an ultra-wideband linear-to-circular polarization converter. Simulation results show that the MS can realize high-efficiency and ultra-wideband linear-to-circular polarization conversion under both u- and v-polarized incidences; the axial ratio (AR) of the reflected wave is below 3 dB in the ultra-wide frequency band of 6.45–24.20 GHz, which is corresponding to a relative bandwidth of 116%; in addition, the polarization conversion rate (PCR) can be maintained larger than 99.5% in the frequency range of 6.78–23.70 GHz, which occupies 95.3% of the 3 dB-axial-ratio-band. Finally, an experimental verification is carried out, a good agreement between the experimental and simulation results is observed. [ABSTRACT FROM AUTHOR]