Recent advances in RF tomography for underground imaging

Underground imaging for tunnel detection is proposed using the principles of radio frequency (RF) tomography. In RF tomography, a set of distributed transmitters and receivers are deployed arbitrarily above the ground, or slightly buried. These transmitters radiate suitable narrowband, low-frequency waveforms into the ground. The resulting wavefront impinges upon underground objects, scattering electromagnetic energy in all directions. Receivers sample the scattered signal, mitigate direct-path leakage, retrieve the phasor of the scattered signals, and relay this information to a base station. After adaptive processing of measured data, an image of the underground facilities is achieved.