Equivalent surface impedance of devices based on cavities in endless and ideal conductive screen

In EHF device is often required to create a surface with some law of impedance change (for example, an aperture of satellite antennas with the special geometric form and given radiation pattern, intended for remote sensing, of planets). Such surfaces may be based on cavities in a conductive screen. These designs have some degrees of freedom for regulation of an impedance. Filling in cavities materials with final conductivity and/or anisotropic materials, it is possible to control both the active and jet components of equivalent surface impedance over a wide range. The obtained results can be used for creation a microwaves devices on the basis of impedance surfaces.