Curvilinear Antennas Above a Spherical HIS

A novel artificial magnetic conductor (AMC) ground plane with spherical curvature is proposed. The metallic patches used to form the high impedance surface (HIS) ground plane are of circular periodicity. A detailed description on the design procedure and reflection phase characterization of such ground planes is provided. The impact of the curvature on the reflection characteristics and the maximum curvature which can be applied to the flat HIS are also examined. Two curvilinear antenna elements (loop and spiral) are located above the designed ground plane, and their performances are compared when the two are placed on a flat HIS. Measurements are performed to validate the simulations. An excellent agreement is attained.