Design Methodologies for Dual-band Modulated Metasurface Antennas

This paper presents two different design methodologies to cope with the somehow unexplored design of dual-band modulated metasurface (MTS) antennas with circular shape. In the first approach, one overlays two different modulations. Each modulation is appropriately chosen to provide a broadside beam for one of the bands and a very weak radiation for the other frequencies. The second approach builds on the active region modulated MTS concept, recently applied to broadband designs. In this case, the periodicity of the modulation at the central region of the aperture is selected to radiate at the high frequency band. In turn, a larger periodicity in the outer annular region provides the broadside beam at the low frequency band. Both approaches are compared and their advantages and drawbacks, discussed.