Microwave Tomography System for Reinforced Concrete Structures

This paper is devoted to a new imaging technique for the Non-Destructive Testing (NDT) of civil engineering structures such as bridges. This technique uses microwave radiation to interrogate the concrete medium in a reflection mode configuration. The backscattered electromagnetic field, generated by the presence of the rebars, is measured with a linear sensor probe array and processed numerically in order to provide tomographic images of the volume under investigation. A compact prototype of a so-called Microwave Camera operating in the microwave X-band region between 7-13 GHz with frequency diversity is presented. Computer simulations for theoretical performance limit study as well as experimental performance, evaluation of the prototype have been conducted on reinforced concrete slabs with practical configurations and on a bridge beam. The performance has been compared with that of magnetic metal detectors which are available on the market.