Electromagnetic analysis of permeability and permittivity of coated material on waveguide slot antenna

Electromagnetic wave characteristic of slot antenna at rectangular waveguide is discussed in this study. The rectangular waveguide is attached to infinite ground plane, and on the ground plane, one layer of coating exist. Material of coating layer is assumed that has arbitrary permeability, permittivity, thickness, and loss tangent. The aperture field distributions, far-field radiation patterns are extracted from electromagnetic field analysis. To analyze the electromagnetic field, the theory of continuity of the magnetic field is forced boundary condition from the waveguide, through coating layer, to free-space. By forcing boundary equations, the spatial domain and spectrum domain Green´s function for internal and external are derived. By based on Green´s functions, integral equations are obtained and these integrals are solved by using numerical methods. After solving the equations, the field components are obtained. Aperture electromagnetic field and far-field radiation pattern of the waveguide slot antenna are available using the method of stationary phase.