Comparison of the fast multipole method and low rank IE-QR algorithm in the analysis of electromagnetic field in the focal region of a parabolic reflector

This paper describes scattered field calculation in the focal region of a parabolic reflector under uniform plane wave illumination. Method-of-moments (MoM) with integral equations method (IE) is used to calculate the current induced on the reflector. Paraboloid antennas are electrically large objects, so linear equations contain a large number of unknowns (tens of thousands or hundreds). To speed up solution the fast multipole method (FMM) and low rank IE-QR algorithm are involved. Results for ideal and distorted reflectors obtained by MoM, FMM, low rank IE-QR are given and compared with calculations done by other authors.