A Metasurface-Based, Ultrathin, Dual-Band, Linear-to-Circular, Reflective Polarization Converter: Easing uplinking and downlinking for wireless communication

In this article, an ultrathin (+m/15), dual-band, reflective-type linear-tocircular (LTC) electromagnetic (EM) wave-polarization converter is reported. The LTC-polarization conversion has been achieved at two distinct frequency bands viz., 8.34 to 8.71 GHz and 10.3 to 14.73 GHz. In the first band, the structure behaves as a right-hand circular polarization (RHCP) converter, whereas, in the second band, it works as a left-hand circular polarization (LHCP) converter. In both of the frequency bands, the structure exhibits a high-energy conversion efficiency (ECE) of more than 80%. The structure exhibits a 3-dB fractional bandwidth of 39.4% with respect to the center frequency at the higher band while maintaining an axial ratio (AR) of lower than 3 dB in both the frequency bands. To validate the simulated results, the experimental characterization of the proposed metasurface (MS) design has also been carried out in this article. The experimentally measured 3-dB AR bandwidth has been found to be in good agreement with the simulated one. The structure provides angular steering stability up to a 30° incident angle, resulting in its application with beam scanning antennas. The proposed device integrated with antennas may find potential applications in easing the switching of polarization states between uplinking and downlinking for wireless communication in space research as well as in military radar applications.