Electromagnetic (EM) research involves examination of deposit conductivity induced by electromagnetic field. The measurement system is two coils: transmitting and receiving. The transmitter produces a primary electromagnetic field which generates a secondary electromagnetic field in the deposit. Receiver coil records secondary field size and the ratio between the primary and secondary field. VLF (Very Low Frequency) method examine the secondary fields produced by the conducting deposits, found in soil, which are subjected to the original EM signal. This is a passive method that uses radiation of strong military radio as the primary signals.
