Magnetic Gradient Sensor

In magnetic surveys it is often more useful to deal with the magnetic field gradients than with the field itself. This paper describes a device which measures magnetic field gradients directly and which is not influenced by uniform magnetic fields. Even if asymmetries exist in the device, the constant part of the magnetic field will appear as a signal with a frequency much different from the signal produced by the field gradients, and this can be easily filtered from the output. Test results on a research model are presented.