Abstract: A probe serving for detecting the structure of a dielectric medium. The probe includes at least one transmitter/receiver antenna located near a dielectric boundary surface that defines a dielectric medium, and a signal processor for receiving signals from the antenna and generating data representative of the structure of the dielectric medium. Between the antenna and the face is inserted a cushion of a material having a dielectric number higher than that of the air. In one embodiment, the probe is adapted to inspect if there is a void in the soil around a dielectric pipe, for example a sewer pipe. In this case, the probe is guided inside the pipe with the antennas located on a shaft mounted on the probe with the same axis as the axis of the pipe. Due to the presence of the cushion, an optimally good connection between the antennas and the face defining the dielectric medium is obtained.