A Square Helmholtz Coil is a pair of identical circular coils parallel to each other. The distance between the two coils is equal to the coil radius, and the winding method makes the current flow through the two coils in the same direction. This winding method produces a uniform magnetic field between the two coils, the major components of which are parallel to the axes of the two coils.

The uniform area of ​​the Square Helmholtz Coil is large, spacious and easy to handle. It can realize one-dimensional, two-dimensional and three-dimensional combined magnetic fields, and can provide AC and DC magnetic fields. The current has a good linear relationship with the magnetic field.
Square Helmholtz Coil is suitable for various scientific research institutes, universities and enterprises to conduct material magnetic or testing experiments, and is suitable for materials, electronics, biology, medicine, aerospace, chemistry, applied physics and other disciplines. Its main purpose: to generate standard magnetic field; offset and compensation, geomagnetic environment simulation, determination of magnetic shielding effect, electromagnetic interference simulation experiment, calibration of Hall probe and various magnetometers, research of biological magnetic field and research of magnetic properties of materials.
Applications for the Square Helmholtz Coil include removing the Earth's magnetic field, generating magnetic fields for experiments, and applications that require such fields. Depending on the field of application, the generated Helmholtz magnetic field can be a static magnetic field, a time-varying DC magnetic field or an AC magnetic field.