Limitations of characterizing layered earth with off-ground GPR

A detailed analytical feasibility study is performed which identifies several important limitations in the problem of layered earth characterization with off-ground GPR in the mono-static or small baseline bistatic configurations.It is shown mathematically that the characterization of layered earth by radar is an ill-posed problem.The permittivity and thickness of the first layer may be estimated.However, for penetrable earth, one may not estimate the first layer's conductivity or the parameters of deeper layers without ambiguity.This problem may be partially circumvented via the use of a priori knowledge and several examples of this, applicable to practical problems, are considered in detail.The feasibility study identifies the limitations in question in the form of a mathematical proof.These limitations are demonstrated using extensive simulated and experimental results.