Radar Tomography: Sustainable Bridges  Background document SB3.8

Among different ways of radar data acquisition, tomography has so far not been fully investigated yet. In some cases, traditional B-Scan imaging does not give the operator a full idea of the integrity of civil structures, so tomographic imaging of radar data can provide more detailed information. However, it is much more time consuming than the traditional reflection mode and thus should be used on selected areas only. It requires skilled operators to perform data acquisition and analysis. In addition, radar equipment required to perform a measurement is more sophisticated and expensive. Thus, a guideline for radar operators containing detailed procedures for transmission measurements is presented. Conclusions for UMinho experiments - Attenuation tomography was successfully used to compare results from a velocity tomography - Positions of antennas close to concrete (masonry) edges should be avoided - In case of pillars or walls with an access to more than 2 sides it is advised to perform transmission measurements with full ray coverage (measurements from all sides) in order to increase information needed to detect for example air layers inside concrete or masonry structures. - Areas for testing should be chosen due to antenna penetration possibilities. Each of aradargrams obtained during a measurements should have a strong signal at the receiverantenna