Deemphasizing low frequency defects in GTD analysis of pulsed signal scattering by a perfectly conducting flat strip

Geometrical theory of diffraction (GTD) based wavefront, resonance and hybrid formulations of transient scattering by targets, while adequate to generate resonance frequencies, yield incorrect late time scattered fields because of the early time (high-frequency) nature of GTD asymptotics. Thus, impulsive signals are improperly treated in this manner. However, for signals with low frequency cutoff, deemphasizing the low frequency range may eliminate the troublesome portions of the GTD algorithm. This is confirmed here for plane wave scattering by a perfectly conducting flat strip when the exciting pulse has a raised cosine shape. The solution is now stabilized and compares very well with an exact solution obtained by eigenfunction expansion. This suggests that the GTD method can be employed with confidence for transient scattering responses for a class of input pulses with sufficiently weak low frequency content.