Effect of noise and localization error of magnetic field sensors on the characterization of complex sources

Magnetic multipole images are used for characterization of complex magnetic sources. We simulate the multipole imaging of the source by application of selective functions to measured magnetic fields. The objective of this work is to determine the effect of sensor nonidealities on the accuracy of the source characterization. The source is assumed to be within a spherical boundary. The sensor array is arranged in a plane below the boundary, with the axis of the boundary coincident with the symmetry axis of the array. Sensors are radially directed away from the axis of symmetry and are characterized by their noise, offset between the real and ideal position and the deviation of the axis from the radial direction. Several sample sources, consisting of one or two dipoles, were evaluated. The radial component of magnetic field was measured with the planar array of 208 sensors a distance of 15 m below the source. The magnetic field was restored from the spherical expansion coefficients up to eight degree.