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Electromagnetic imaging of layered building materials

Knowledge of the electromagnetic properties of building materials is becoming increasingly important in modern wireless communications due to high demands for indoor communications. This paper describes a free-space time-domain measurement technique, which is based on the principle of ground penetrating radar (GPR), for imaging building materials. The technique can simultaneously determine the constitutive parameters of the layered material being tested, such as the number of layers and the thickness and dielectric constant of each layer. This is achieved by employing an inverse scattering algorithm developed previously. The measurement apparatus and the calibration procedure are described. Results of measurements on standard materials and some building materials are presented and discussed.