Quasi plane wave generation using periodic structures on slab guide

A compact, flat and low cost setup to generate a quasi-plan wave is described. The setup consists of a dielectric slab guide with its bottom surface covered by metallic ground plane and the top surface carries a conducting thin layer of periodic structure. The slab fundamental Eigen mode propagates in the direction of the periodicity with the electric field component being polarized tangential to the slab surface. The periodic structure causes this wave to couple into a plane wave of finite transverse size in the direction normal to the surface of the slab. Analytical formulas are derived, and the structure is simulated using full wave simulations. Reasonable agreement between numerical and analytical calculations is obtained. The setup can be used in antenna measurement applications.