On the determination of phase and group velocities of dispersive waves in solids

Abstract

A new technique is developed to determine the dispersion relation and the propagational speeds of waves in dispersive solids. The phase spectrum of a broadband pulse is linearly related to the dispersion relation of the dispersive medium. The method is simpler than the continuous-wave phase comparison technique. Application is made to measure the phase and group velocities of waves in fiber-reinforced composite materials and in thin wires. This technique is expected to be applicable to measurements of acoustic or electromagnetic wave speeds in other dispersive media.