Analysis of twisting of search coil leads as a method reducing the influence of stray fields on accuracy of magnetic measurements

The twisting of a pair of leads connecting to a search coil used for detection of magnetic field or flux density reduces errors due to stray magnetic fields. Although this method is commonly used, the influence of stray fields is often underestimated. This could lead to degradation of the accuracy of measurements. This paper presents an analysis of the influence of the quality of wire twisting and its possible influence on the signal-to-noise ratio. Twisted wires are approximated as a two-dimensional configuration, for which typical results of calculations are presented. The paper also reports the results from measurements using manually and machine-twisted pairs of wires. The analysis shows that the stray field influence can be reduced by up to 60% by proper twisting of a pair of wires connecting a sensor to measuring equipment.