Wide range absorption metal sensor - has hidden detector which acts as aerial to attenuate radiation

摘要

The method of location of conductors of unknown length is based on the measurement of the absorption of electromagnetic energy from a transmitting device whose frequency is varied over a wide range. Electromagnetic radiation from a wide-range frequency wobbler is transmitted by means of a conventional dipole aerial or coil. This antenna scans the region in which the conductor is located and the radiation is damped when its frequency coincides with the resonant frequency of the unknown conductor. The magnitude of the damping provides an indication of the dia. and the position of the antenna serves for location purposes. The method may be used to defuse parcel bombs or locate cables buried in buildings.