Beam antenna with circular polarization rotation switching based on passive components

A new type of passive circularly polarized beam antenna with high radiation efficiency and polarization rotation switching capability is proposed, based on phase-nonreciprocal metamaterial. The proposed design implements circular polarization rotation switching by means of an external dc magnetic system non-interfering with the signal path. The planar antenna with a working area of less than 6 cm in diameter demonstrated radiation with 11 dBi gain in broadside direction and circular polarization with axial ratio higher than 0.8 at 7.1 GHz.