Time domain version of the uniform GTD

The uniform geometrical theory of diffraction (UTD) solutions can be inversely transformed analytically to obtain a time-domain version of the UTD. The time-domain solutions are valid in the early time period where an observation time t is close to the time after the arrival of the first diffracted wavefront. Comparisons with GTD (geometrical theory of diffraction) and also with available rigorous results (J.B. Keller and A. Blank, 1951) reveal that the UTD solutions are accurate for substantial early time periods while the GTD (Keller and Blank) results are valid for very early time periods.<
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