Magnetic field nulling

An apparatus for nulling a magnetic field within a nulling region in an ambient magnetic field comprising:

• a plurality of separate magnetic field generating elements placed at separate respective locations surrounding the nulling region for generating respective nulling magnetic fields extending into the nulling region, wherein the plurality of magnetic field generating elements are arranged in a first array;
• a plurality of magnetic field sensing elements placed at a plurality of separate respective locations within the nulling region for sensing respective values of the magnetic field within the nulling region wherein the plurality of magnetic field sensing elements are arranged in a second array and the size of a diameter of the second array of magnetic field sensing elements is at least 30% of the size of a diameter of the first array of magnetic field generating elements;
• and
• a feedback control unit for controlling the values of the respective nulling magnetic fields generated by each of the plurality of magnetic field generating elements in response to values of the magnetic field sensed by the plurality of magnetic field sensing elements by driving the magnetic field generating elements with respective electric currents that reduce the magnetic field values detected by respective magnetic field sensing elements to values not exceeding a pre-set threshold value corresponding to a pre-set nulling of the magnetic field within the nulling region.