A comparison of geometrical theory of diffraction and integral equation formulation for analysis of reflector antennas

Four two-dimensional reflector antennas, the Strip, the corner, the trough, and the inverted trough, are analyzed independently by both the geometrical theory of diffraction (GTD) and integral equation formulation (IEF). A comparison of the radiation patterns calculated by these two methods shows that for intermediate-sized structures ( ), the agreement between the two methods is excellent. (Comparison with measured patterns is given where these are available in the literature.) Extensive calculations are also carried out to determine the ranges of validity of the methods, i.e., exactly how small a structure GTD can treat and how large a reflector IEF can adequately handle. A qualitative assessment of the relative merits of the two methods is also presented.