Displacement Frequency Characteristics of Direct Transmission of GPR Signals in Borehole Measurements

We present results of electromagnetic logging in a borehole with a 50 MHz dipole antenna. The GPR survey was carried out in flooded vertical borehole to a depth of 40 meters through differing geological strata. We measured characteristics of the amplitude-frequency spectrum of the probing signal, which varied depending on contact media in the borehole. In particular, we considered two parameters of the amplitude-frequency spectrum: the average frequency and the spectral width of the energy level. Our analysis of the average frequency offset and the width of the amplitude-frequency spectrum of the electromagnetic signals showed that with the passage of the unshielded linear antennas through the water-filled borehole depended on rock properties around the borehole.