A flat-topped leaky-wave source for phased arrays with reduced scan losses

This paper describes the design of a planar Fabry-Perot leaky wave antenna generating a flat-topped radiation pattern. The flat-topped pattern is achieved by exciting various leaky-wave modes between a metallic ground plane and a superstrate. Two configurations for the superstrate structure are proposed and analyzed: i) dielectric layers; ii) impedance sheets. In all cases, the antennas are fed by a small waveguide opening in the ground plane. An in-house optimization tool based on a Green's function spectral approach is used to derive the appropriate arrangement for the generation of the required flat-topped pattern. The proposed approach is validated numerically for an antenna generating a flat topped pattern in an angular range of ±25°. The proposed flat-topped antenna may be used for the design of phased arrays with reduced scan losses over a given angular range.