An algorithm to identify the structure of electromagnetic fields

In the study of generation mechanisms of electromagnetic radiation observed in laboratory experiments on the interaction of relativistic electron beams with plasma, the problem of determining the structure, spectral characteristics, and power of the emitted electromagnetic waves arises. So, in the numerical solution of Maxwell's equations, there is a need to develop accurate, efficient, and reliable methods for implementing open boundary conditions that allow electromagnetic waves to exit the computational domain without reflection. The linear Maxwell's equations describe the propagation of electromagnetic waves in vacuum and, therefore, it is possible to easily find the frequencies and amplitudes of passing and reflected waves using the Fourier analysis and to determine their structure. In order to study this question, it is sufficient to consider the problem in the two-dimensional case. The aim of this paper is to develop a method of determining the directions and amplitudes of all electromagnetic waves in a vacuum that are in the computational domain at a certain instant of time.