A Low-Profile Transmissive Metasurface For Transformation Of Plane Wave To Contour Beam Pattern Using 4-Arm Spiral Element

A low-profile transmissive metasurface is proposed to synthesize contour beam pattern for a European region. A slot array feed is used to illuminate same size metasurface aperture with a plane wave at a near field distance of 24 mm. A two step optimization process is proposed to solve asymmetric and complicated pattern synthesis problem for transformation of plane wave to contour beam pattern using modified Alternating Projection Method (APM). A new subwavelength 4-arm spiral element is proposed to achieve desired performance for contour beam pattern synthesis in $Ku$ band centered at 12.5 GHz. A prototype of low profile transmissive metasurface is also fabricated and measured to verify its gain and bandwidth performance for contour beam pattern synthesis for the European region.