Numerical Analysis of Dispersion Compensation for Guided Electromagnetic Waves in Rectangular Microwave Waveguides

Guided electromagnetic waves have been proposed recently as a novel technique for surface damage detection in metallic structural components. One limiting factor is frequency dispersion, which causes an emitted pulse to spread out in space and time as the wave propagates. This paper presents a dispersion compensation technique, originally introduced in the field of guided ultrasonic waves, that significantly improves localization accuracy by nonlinear mapping from time to distance domain exploiting a-priori knowledge about the dispersion characteristics. The method compresses the dispersed signal to its original shape. An application of the technique is presented in this paper considering damage localization in a complex WR 28 waveguide covering the frequency band from 20–40 GHz. Therefore, the fundamental dispersion relationships for phase and group velocity have been derived. The results show a strong compression of the waveforms through dispersion compensation leading to an improved localization with an error of less than 1%.