Design of a modulated dielectric metasurface antenna

A special kind of spiral planar circularly polarised (CP) antenna is presented. These antennas are based on an interaction between a cylindrical surface wave excited by an omnidirectional probe and an inhomogeneous surface impedance with a spiral pattern. The surface impedance interaction transforms a bounded TM0 surface wave into a circularly polarised leaky wave with almost broadside radiation, through a grounded dielectric slab with a spiral sinusoidal thickness, modulated in the radial direction by a polynomial. Full wave results are in perfect agreement with the theory previously outlined in the literature.