Research on Dual Frequency Metal Detector

With the method of equivalent impedance,this paper analyzes the metal target characteristic of amplitude and phase of low frequency electromagnetic induction signal,the theoretical basis and design of dual frequency,and the relationship between the dual frequency and sensitivity.This paper also researches the design of multi-layer printed circuit board receiving coil and phase shift coil,the method of automatic controls,the effect of conductive and magnetic background signal caused by seawater and magnetic ground,and presents the method of automatic tracks and the direct current shift caused by climate condition.