Metal Detection Basics

The Basic Principles

Most modern metal detectors operate on the balanced coil, full loop system.

Three coils are wrapped around the aperture through which the product passes. In the centre of the enclosure is the transmitter coil that broadcasts a radio frequency signal and generates an Electro-Magnetic field.

Equally spaced on either side of the transmitter coil are two receiver coils. (Figures 1 & 2).

The field is generally trapped inside the shielded enclosure of the detector but some field escapes from the aperture on both sides of the detector. Anything that enters in this field that is either Magnetic or Electrically Conductive will cause a disturbance in the field strength around it. All metals have either one or both of these characteristics and will be detectable if the size of the signal is large enough.

The signal from the receiving coils are connected in opposition to each other and therefore when no disturbance is occurring there will be a net signal of zero across the coils – they are balanced. This forms the electrical equivalent of a balanced weigh scale.

As metal contaminant passes through the aperture, the balance will be offset. This disturbance is amplified and analyzed by the control electronics and detection will occur if the sensitivity threshold has been exceeded.

But what is the recommended usage? What are the best practices for installation? What are the latest features? Which type of metal detector is right for your application?

Regal has the answer to these and many more in depth questions regarding metal detection technology. Feel free to call us at (630) 942-8461.