Beam expansion in multi-reflector quasi-optical systems

This paper presents an analytical field expansion in terms of a new type of conical beams in a segment of beam waveguide (BWG). In BWG problems, one can often deal with reflectors of size about several hundred wavelengths, so that reducing the number of wave propagator in the field expansion can significantly save computational time. The algorithm starts on a sampling of the equivalent currents on an auxiliary plane and relevant FFT calculation, from which the weights of the beams are determined by an automatic process. Numerical examples show an accuracy of the expansion within a dynamic of 55 dB.