UNDERGROUND TOMOGRAM FROM CROSS-BOREHOLE MEASUREMENTS

Cross-borehole multifrequency continuous-wave radar measures the ampli tudes and phases of the transmitted fields. This makes it possible to calculate the permittivity and conductivity averaged along the line co nnecting two receiving antennas with the transmitting antenna in the b oreholes. Backprojections of these line-averaged parameters in the par allel and offset measurements give stable and smooth tomograms of subs urface permittivities and conductivities, except for isolated high-con trast objects such as the air tunnel. (C) 1998 John Wiley & Sons, Inc.