RADAR
Ground penetrating radar produces a continuous, cross-sectional record of subsurface features. The records are used to locate reinforcing steel and voids in the concrete. The radar system consists of an antenna housing and a control unit. The antenna housing contains both the transmitting and receiving antennas. The high frequency radio waves are reflected from the subsurface features and they are stored in the digital control unit. As the antenna is moved along the surface, each new echo is plotted alongside the previous echos forming a pattern which is used for interpretation.