Ray-oriented design of Huygens metasurfaces for multiple source excitation

Huygens metasurfaces (HMS), combining subwavelength electric and magnetic polarizable particles, have demonstrated impressive wave manipulation capabilities, such as engineered refraction, focusing, and polarization control. Recently, a general methodology to design HMSs for converting given (arbitrary) source fields to directive radiation has been presented, facilitating antenna design (A. Epstein and G.V. Eleftheriades, IEEE Trans. Antennas Propag., 62, 5680–5695, 2014). However, this methodology guarantees proper performance only for the designated source excitation, whereas for many modern applications multifunctional devices, e.g. multidirectional antenna, are desirable.