Multifrequency Band Synthesis of Modulated Metasurface Antennas

We present and discuss the synthesis of modulated metasurface (MTS) antennas capable of radiating multiple beams at multiple frequencies. The proposed technique is built on a recently developed integral equation formalism. Assuming that the MTS can be homogenized over the whole frequency band, the sheet impedance describing the MTS can be accurately modeled w.r.t. the frequency. This allows us to simultaneously establish multiple systems of equations standing for a design at different frequencies, and possibly different feed points, and to solve the overall problem in the least-squares sense. The method can be used either for improving the antenna bandwidth (if the frequencies of interest are relatively close) or for multiplexing several applications operating at different frequencies. Several synthesis examples are provided and numerically validated.