Physical optics analysis of beam waveguides using auxiliary planes

A physical optics (PO) method is presented which in two steps calculates the scattered field of a reflector or a lens in a beam waveguide (BWG). The first step involves a calculation of a set of currents on an auxiliary plane and the second step a field calculation from this current set. The method is named A-PO that refers to the calculation of PO currents on an Auxiliary plane. A-PO is less accurate than PO for sidelobe analysis, but useful for first-pass analysis of the main beam region in a BWG where it is significantly faster than standard PO. Two examples show that the co-polar as well as cross-polar radiation in a submillimeter BWG can be efficiently determined 40 dB below peak.