Complete Open-Stopband Suppression for Anisotropic Modulated Metasurfaces Scanning Through Broadside

In this paper, it is shown that circularly polarized leaky-wave (LW) antennas based on a one-dimensionally modulated anisotropic impedance exhibit a complete suppression of the open-stopband when the beam is scanned through broadside. This is in contrast with what happens in an isotropic periodically modulated impedance surface. This general behaviour is illustrated here by using a homogenized penetrable impedance model to compute the LW dispersion. As a consequence, LW antennas based on modulated anisotropic metasurfaces (MTSs) are able to scan from backfire to endfire without any frequency region of high attenuation.