Ultrasonic wave transmission in a porous material as a function of frequency and incident direction was investigated, both theoretically and experimentally. The aim of this study was to determine the optimal frequency and incidence direction for the most penetrating ultrasonic radiation into sediment. The results can be applied towards the detection of underground objects, in particular, the detection of non-metallic objects such as mines currently undetectable with metal-detectors. Computer software was developed to determine the dispersion characteristics of ultrasonic waves in fluid saturated media of packed spherical grains in the 50μm to 3000μm size range. The wave frequency range was from 0.1 MHz to 10 MHz. The results showed that Biot’s theory could not be used to explain the observations without significant modification. Good agreement between theory and experiment could finally be obtained with the modified theoretical approach.

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