Optimization of 3D multilevel non-uniform grid back-propagation algorithm by using modified oblate spheroidal coordinates

A large class of source imaging methods is based on the radiated field backpropagation, often referred to as antenna holography, which has been widely used for large reflector antenna analysis. In these methods, the field is measured in either the near- or far-field zone of the source, by using a probe whose influence on the measured data is compensated. The measured field is propagated back to the source surface and the resulting reconstructed distribution is compared to the desired one. The comparison allows for the localization of distortions in the source´s topography or current distribution. Although back-propagation does not accurately recover the original source distribution, it provides a good approximation of the radiating subspace of source distributions, up to an error due to the truncation of the measurement surface.