Circularly Polarized Horns Based on Standard Horns and a Metasurface Polarizer

A method for designing circularly polarized (CP) horn antenna is proposed, which is based on a standard pyramidal horn with a linear-to-circular polarization transformer. A compact transparent metasurface transformer is first designed to perform linear-to-circular polarization transformation, and then this is inserted in a linearly polarized standard pyramidal horn to create a CP horn. To validate the CP horn design, both simulations and experiments were conducted and good agreement was obtained. The CP performance achieved a 3 dB axial-ratio bandwidth of 7.4%, a maximum gain reduction of 1.1 dB without altering the horn's original size for a light increase in weight and at a small cost increase.