Dual Subwavelength Fabry–Perot Cavities for Broadband Highly Directive Antennas

A new concept for designing broadband and subwavelength profile Fabry-Perot-type antennas is introduced. A novel multilayer periodic array design is proposed, yielding two subwavelength-profile Fabry-Perot cavities that significantly enhance the bandwidth performance of the resulting highly directive antenna. The design is based on two optimized double-layer periodic arrays of dissimilar dimensions, each double-layer array consisting of a capacitive artificial magnetic conductor (AMC) layer and an inductive partially reflective surface (PRS) layer printed on either side of a dielectric substrate. They are placed at about a quarter-wavelength distance from a ground plane and from each other. Thus, two air cavities are created with a total profile of less than λ/2. The proposed antenna has been simulated in CST Microwave Studio, achieving 18.3 dBi directivity with 8% bandwidth.