Subsurface Exploration Systems for Shallow Geophysics

The paper considers the performance features of subsurface exploration radio-wave systems. It was shown that to solve the problems of shallow geophysics, it is reasonable to use dipole (vibrator) antennas. The paper describes the new developed georadar antenna assembly type based on the combination of electric and magnetic type dipoles. The proposed antenna assembly consists of a radiating symmetrical vibrator antenna, which is, in fact, an EH-antenna, and a receiving two-section magnet antenna, which, beside its main functions also fulfills a correction function aimed at providing the necessary phasing between the created electric E and H magnetic fields. At the same time, axis structural alignment of the vibrator antenna and the ferroprobe provides their deep coupling by the primordial radiated electromagnetic field. Thus, in the proposed antenna module design, the radiating vibrator EH-antenna forms the effective structure of the radiated electromagnetic field of maximum intensity in the environment in the near-field region while the receiving magnetic antenna provides the improved response due to transfer of the magnetic antenna to the maximum sensitivity region by magnetic biasing of its core made from ferromagnetic dielectric material and this magnetic biasing is provided by the additional direct current source. Due to modulation carried out in the ferroprobe, the signal amplification takes place at a significantly higher frequency than the measured field frequency, which results in simplification of secondary measuring transducers designs, which, in its turn, contributes to phase distortion minimization during desired signal amplification.