More about VLF

Our instrument utilizes the magnetic components from the electromagnetic field generated by military radio transmitters that use the VLF frequency band (Very Low Frequency 15-30 kHz). They are used mostly for long-distance communication. The magnetic field lines from such a transmitter are horizontal, with the field lines aligned in concentric circles around the antenna.

When the electromagnetic field from a VLF transmitter passes through a conductive body, secondary currents will grow up in the body. This is the principle of induction. These secondary currents will in turn generate a magnetic field, a secondary field, which will try to repell the primary field. This field can be measured and analyzed. Our instrument measures the field strength and phase displacement around a fracture zone in the rock.

These results are displayed and are easy to read and understand.