Electromagnetic wave propagation in concretes

The interpretation of results of radar testing of structural concrete has been hampered by a lack of knowledge of the fundamental dielectric properties of the material. Efforts have been made by a number of researchers to develop theoretical models taking account of the known properties of concrete constituents and their proportions. These have considered inter-relationships between moisture content, voids and test frequency. Other work has examined parameters such as coupling effects on beam spread angle and effective signal frequency in concrete for some commercially available antennas with nominal centre frequencies between 500 MHz and 1 GHz. However, it must be concluded that whilst measurements at discrete frequencies provide a valid approach for comparison of materials compositions, they are not directly applicable to interpretation of field measurements using antennas of similar nominal centre frequency