手持金属探测器利用电磁感应的原理，利用有交流电通过的线圈，产生迅速变化的磁场。这个磁场能在金属物体内部能感生涡电流。涡电流又会产生磁场，倒过来影响原来的磁场，引发探测器发出鸣声。手持金属探测器的精确性和可靠性取决于电磁发射器频率的稳定性，一般使用从80 to 800 kHz的工作频率。工作频率越低，对铁的检测性能越好；工作频率越高，对高碳钢的检测性能越好。检测器的灵敏度随着检测范围的增大而降低，感应信号大小取决于金属粒子尺寸和导电性能。

The handheld metal detector takes advantage of the principle of electromagnetic induction and uses a coil that has alternating current to produce a rapidly changing magnetic field. This magnetic field can produce a eddy current within a metal body. The eddy current produces a magnetic field, which affects the original magnetic field and causes the detector to make a sound. The accuracy and reliability of a handheld metal detector depends on the frequency stability of the electromagnetic launcher, generally using the working frequency from 80 to 800 kHz. The lower the working frequency, the better the testing performance of iron, the higher the working frequency, the better the detection performance of high carbon steel. The sensitivity of the detector decreases with the increase of the detection range, and the size and conductivity of the metal particles are determined by the size of the induction signal.