甚低频（VTF）法是利用甚低频电台发射的电磁波作为场源的电磁勘探方法。电磁波在传播过程中，遇到良导或磁性感应体时，将其极化、而产生二次电流，从而引起感应二次场。二次场与一次场合成后的总场与一次场的振幅、方向和相位均不同，即引起一次场的畸变。通过测量某些参数的畸变，即可发现地下良导或磁性感应体的存在。 Very low frequency (VTF) method is the use of very low frequency radio waves emitted electromagnetic field as a source of exploration methods. Electromagnetic waves in the propagation process, encountered good guidance or magnetic induction body, the polarization, resulting in secondary current, causing the induction of secondary field. After the second field and a field synthesis of the total field and a field amplitude, direction and phase are different, that is caused by a field distortion. By measuring the distortion of certain parameters, you can find the existence of underground conductive or magnetic sensors.