ACTIVE SUPPRESSION OF INTERFERING MAGNETIC FIELD

摘要

A method is proposed to reduce interfering magnetic field by applying reverse magnetic field generated by a negative feedback system. The system consists of a pickup coil, amplifiers and a driving coil. The voltage induce in the pickup coil by the interfering magnetic field is amplified and fed to the driving coil. The magnetic field generated by the driving coil is superposed on the interfering magnetic field to cancel most part of it. The manufactured system successfully reduced the interfering magnetic field in a cubic space of 10 cm x 10 cm x 10 cm by more than 40db.