About Magnetometers
Here we present a simple guide to magnetometers, and specifically fluxgate magnetometers. If you are unfamiliar with these extraordinary devices, we hope this page explains what you’d like to know.
If you want to continue the journey and learn more about our products, take a look at our product brochures, visit our Downloads website, or contact us.
What is a Magnetometer?
A magnetometer is a device that measures the strength and direction of a magnetic field, often the Earth’s magnetic field. The simplest example is the magnetized needle in a compass, pointing to magnetic north. Modern magnetometers produce an electrical output signal and can be used in two ways:
- Static Field Measurement: Measures the background magnetic field, used as a reference for other instruments.
- Dynamic Field Measurement: Detects changes in the magnetic field.
These abilities make magnetometers useful in various applications, including navigation, geophysical surveying, weather forecasting, border and perimeter security, mineral exploration, and scientific research. They are also used to calibrate compasses in smartphones and other electronic devices.
Bartington has been a world leader in designing and manufacturing fluxgate magnetometers for almost 40 years. Our sensors are used globally, from the Poles, ocean floors, and volcanoes to cryogenic environments and space.
How Does a Fluxgate Magnetometer Work?
A fluxgate magnetometer comprises three main components:
- Magnetically Permeable Alloy Core: A material with high magnetic susceptibility that aligns easily with a magnetic field.
- Drive Winding Coil: (black on diagram)An alternating current is passed through it, repeatedly magnetising and demagnetising the core .
- Sense Winding Coil: (red on the diagram)A current is induced in this coil, generating the magnetometer output signal.
Interference with the magnetometer’s stable state induces a deviated electrical current in the Sense Winding coil, indicating the strength of the interfering magnetic signature. For example, a large magnetic object close to the magnetometer produces a larger induced current than a small magnetic object.
This is the basis of a single-axis fluxgate magnetometer, which detects in one direction (one axis).
 Adding two more perpendicular fluxgate magnetometers creates a three-axis magnetometer, allowing three-dimensional measurements of the interfering field’s magnitude and orientation.
Magnetometer Applications
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Defence
Bartington magnetometers are widely used in air(see Aerospace below), land and  marine defence applications for signature measurement, EOD divers, degaussing ranges, and border security. They enhance surveillance and detection in remote and difficult terrain, adding a discriminating factor to identifying threats.
Aerospace
Magnetometers are used in Magnetic Anomaly Detection (MAD) systems for maritime patrol operations. They are also used in airborne surveys for geological mapping, mineral exploration, and pipeline inspection. Terrestrially, our sensors are used to test aircraft instruments and calibrate compasses.
Exploration
Our magnetometers aid in exploration – finding and extracting oil, gas, and minerals, guiding drilling equipment, magnetic ranging, pipeline inspection, and terrain exploration.
Space and High Altitude
Magnetometers onboard high altitude craft and spacecraft monitor space weather, perform direct magnetic field measurements, and serve as reference measurements. They are often mounted at the end of a nonmagnetic mast to reduce interference.
Bartington magnetometers feature in two current space missions: Lunar Vertex and MagQuest.
Security
Magnetometers detect weapons and contraband in security screening. Bartington magnetometers protect people and organisations, securing site perimeters on land and underwater.
There is crossover between defence and security applications, so we group them together in land defence.
Medical
Magnetometers in medicine ensure MRI and NMR scanners are in magnetically stable environments, measuring the 5 Gauss Line. They are also part of feedback loops in active cancellation systems to minimize background fields.
Physics
Fluxgate magnetometers are used in physics applications like EMC testing, sensor calibration, and field monitoring. Our cryogenic magnetometers enable field measurements in extremely low temperatures, such as inside cryogenic chambers, quantum computers, and particle accelerators, measuring down to 2 Kelvin.