METAL DETECTOR

PURPOSE: To detect the presence and orientation of embedded rod and grid by providing an assembly of a magnetically sensitive material, and a monitor for indicating approach of a detector to a conductive material in an external field. CONSTITUTION: An induction unit comprising coils wound around respective cores made of a magnetic material is connected with a capacitor so as to form a resonance circuit. The natural resonance frequency and the shape of an induction unit cause an eddy current loss in an embedded metallic object through electromagnetic coupling thus varying the Q of the resonance circuit. Consequently, the position and direction of a rod embedded in a wall are determined for example by moving the detector on the wall and maximizing the dip signal under steady state. A plane 14 is located above one or a plurality of rods at that moment, and the angle of the rod can be estimated from a peak value at the time of metallic rotation related to the dip signal.