ANALYSIS OF AN ELECTROMAGNETIC INDUCTION DETECTOR FOR REAL-TIME LOCATION OF BURIED OBJECTS

Spatial response characteristics of an electromagnetic induction sensor as it passes over a metallic object are investigated using a simple analytical technique. In this low-frequency technique, one replaces a metallic object with equivalent electric and magnetic dipoles and then applies the principles of reciprocity to obtain the induced EMF in a sensor coil. Analysis is carried out for a sensor employing rectangular coils, and the object set is confined to a sphere and a prolate spheroid. The simple approach, which is illustrated with both numerical and experimental data, is found to be adequate to understand the effect on the response characteristics of parameters such as object depth, orientation, aspect ratio, and material properties. The results clearly bring out the limitations of simple detection and location strategies and reinforce the need for more sophisticated processing to provide accurate buried-object location. © 1990 Canadian Crown Copyright