The TriField Natural EM Meter was designed to do field measurements for special research. It detects changes in extremely weak static (DC or "natural") electric and magnetic fields, and signals with both a tone and the movement of a needle-type gauge if either the electric or magnetic field changes from previous levels.

 

A radio and microwave detector is also included, which reads radio power directly. Because man-made AC electric and magnetic fields are very common and could interfere with readings of static fields, the meter has been designed to ignore AC fields.

 

The meter is sensitive to changes of as little as 0.5% of the strength of the Earth's magnetic field, and the tone will sound whether the field increases or decreases. This meter can also be used to determine if anything is magnetized. The Natural EM Meter can detect geomagnetic storms caused by unusual solar activity interacting with the ionosphere (which results in rapid changes of up to 10% in the Earth's magnetic field), as well as the electrical activity of ordinary thunderstorms. It will signal the movement of any distant, strong magnetic sources in the sky, even if the sky is cloudy or the source dips behind a hill. When the dial is set to ELECTRIC, the meter is sensitive to electric fields as weak as 3 V/m (volts per meter). Human beings and animals usually emit an electric field which is easily detectable using the Natural EM Meter. In fact, the meter can be used as a motion-activated intruder alarm.