A Ground Penetrating Radar System for High Loss Environments

Ground penetrating radar (GPR) is most successful when the electrical conductivity, σ, of the ground is low and scattering losses are low. In that case it is assumed that radiated electromagnetic pulses maintain their shape as they propagate. If σ ~ ωε, where ω is angular frequency and ε is the dielectric permittivity of the ground, this assumption fails and radiated pulses both attenuate rapidly and broaden, resulting in indistinct images of the subsurface. We aim to extend the effective depth of investigation, enhance the clarity of subsurface images, and improve the accuracy of inversion for subsurface electromagnetic properties in high loss earth. We have built a new GPR that achieves high dynamic range by means of a unique phase-preserving linear/logarithmic receiver and real-time signal digitizing and averaging. Back-shielded antennas minimize radiation into the air. The first experimental results in high loss conditions show improvements over previous GPR surveys.