Simulation of paraxial beam propagation using plane wave expansion method

The simulation on propagation of microwave beam from one transverse plane to other transverse plane is useful for applications like phase retrieval of microwave beams propagating from one plane to another. The plane wave expansion method is used for paraxial beam propagation of a given field structure. This method decomposes the arbitrary field distribution in to infinite number of plane waves covering the entire range of directions from the propagation axis. The plane wave expansion is an extension of Fourier transform concept where any arbitrary signal is decomposed into infinite number of frequency components with frequency ranging from -infin to +infin. One can easily propagate the arbitrary field distribution form one plane to other by propagating its plane wave components. The idea of microwave beam propagation using plan wave expansion method is explored. This method is validated for the propagation of a Gaussian beam in free space. The simulation results are verified with analytical calculation.