Arbitrary Transformation of Radiation Patterns Using a Spherical Impedance Metasurface

We present a method to transform the radiation pattern of an antenna into an arbitrarily defined pattern through the use of an inhomogeneous spherical impedance metasurface that completely encloses the radiating source. We derive a general procedure to determine the sheet impedance distribution required to form the desired electric field image pattern. As an example, we demonstrate the ability to transform the radiation pattern of a dipole into the image of a nautical anchor in both the near field and far field. Full-wave simulation results provide good agreement with calculated expectations, confirming the ability to accurately form arbitrary radiation patterns using closed metasurfaces.