Complex Permittivity Retrieval Approach With Radar Enhanced Contrast Source Inversion for Microwave Nondestructive Road Evaluation

In this article, an experimental investigation of microwave quantitative imaging of nondestructive testing (NDT) applications for concrete road structures is presented. A radar prior-based contrast source inversion (CSI) scheme is introduced to achieve an accurate reconstruction for target shape and dielectric property by applying the promising radar approach–range points migration. Moreover, to address the local optimum problem, we introduce an appropriate initial estimate for complex permittivity that focuses on the cost function of the CSI. A numerical and real data from an actual concrete road model, where a thin-layer water-filled cavity is buried into the boundary area between the asphalt and the concrete floorboard, show that our proposed approach improves reconstruction accuracy for permittivity and conductivity in a real NDT model.