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 of
n
2¿). We show that the spatial variability of isolines is determined by a medium physical property change or by the presence of inhomogeneous objects.