An Ultra-Wideband Linear-to-Circular Polarization Converter Based on a Circular, Pie-Shaped Reflective Metasurface

In this paper, we present an ultrawideband reflective metasurface with the properties of an LTC-PC, which is an orthotropic composition with two mutually orthogonal symmetric axes, v and u, and 45 degrees rotation about the vertical y-axis. Based on the metasurface unit cell, it seems like a circular pie embedded with a rectangular patch. The converter can convert LP electromagnetic (EM) waves to CP waves over the bands from 20.18 GHz to 33.93 GHz, with a 3-dB AR bandwidth of up to 50.8% and a circular polarization wave that is RHCP (right hand CP). Moreover, the linear-to-circular PCR exceeds 98% in the frequency bands of 20-34 GHz. A comprehensive theoretical investigation was conducted to determine the fundamental cause of the LTC polarization conversion. The increment phi uv between two reflection coefficients at v- and u-polarized incidences is +/- 90 degrees, which fully anticipates the axial ratio of the reflected wave. Any reflective metasurface can be used as an efficient LTC-PC if the increment phi uv is close to +/- 90 degrees.