Phase Spectrum of Signals in Ground-Penetrating Radar Applications

The phase structure of ground-penetrating radar (GPR) signals operating on the basis of a stepped-frequency continuous wave (SFCW) is extracted to obtain additional information about the physical properties of buried objects. The phase structure is obtained from a signal-phase-frequency spectrum by applying the discrete Fourier transform to signals on the output of an SFCW georadar quadrature phase detector. We show that the phase gradient of a phase-frequency spectrum of signals reflected from underground layers and buried objects is determined by their electrical properties. We represent a signal phase structure during the georadar movement along the ground surface as an image of phase isolines (lines corresponding to the phase shift ofn2¿). We show that the spatial variability of isolines is determined by a medium physical property change or by the presence of inhomogeneous objects.