Fast irregular electromagnetic field transformation utilizing spatial or spectral equivalent sources representations together with hierarchical radiation operator evaluation

Arbitrary high-frequency electromagnetic fields sampled by arbitrary field probes are efficiently transformed by hierarchical plane wave based evaluations of the radiation operator for equivalent sources representing an antenna or a scatterer. The equivalent sources can be either electric and magnetic surface current densities in the spatial domain or it is possible to directly work with various spectral domain representations of these sources on varying levels of the radiation operator hierarchy. The resulting inverse problems are efficiently solved by an iterative equation solver. Large scale radiation and scattering applications for synthetic and measured field data are investigated.