THE RING CORE FLUXGATE SENSOR NULL FEED-THROUGH SIGNAL

The fluxgate null feed-through signal is discussed theoretically giving an expression for the excitation current and for the core flux coupling coefficients to the secondary coil. Experimental results show that the two signals cannot be nulled simultaneously by rotating the core inside the secondary coil, and give the two coupling coefficients. The excitation current coupling depends critically on the symmetry of the winding, and it is shown that the two signals are associated with excess noise adding to the basic core noise.