Microwave imaging of buried objects for ground radar tomography

摘要

The detection and identification of buried inhomogeneities using electromagnetic waves are of great importance for nondestructive testing in geophysical, civil engineering, military, or humanitarian applications. The approach described here uses a linear inversion algorithm based on diffraction tomography to process the backscattered field signal generated by the buried inhomogeneities, measured over a probing area, for computation of a tomographic image of the ground. The technique has been extended to cater for time pulse (synthetic pulse or real pulse) illumination and to incorporate the near-field radiation pattern transmitted by a broadband antenna. The backscattered field is measured at various locations with a receiving antenna for different positions of the transmitting antenna. The main advantages of such a method are the use of explicit formulas for solving the imaging problem and the possibility of rapid image display thanks to the use of Fast Fourier transform to implement the reconstruction algorithms on PCs. First, a number of tomographic reconstructions of buried objects are given for situations of practical interest. Results of numerical simulations with a Rayleigh incident pulse in the frequency band [0.3,3.0] GHz and the use of a bow tie antenna in the frequency band [0.3,1.3] GHz are presented. Second, tomographic reconstructions of buried objects are presented and discussed, to demonstrate the influence of object dielectric properties versus soil electromagnetic parameters.