Patent ID: 7495624

Claim:
An apparatus for detection of the gradient of a magnetic field, which has the following: a) at least four antenna elements ( 11 , 12 , 13 , 14 ) composed of a ferromagnetic material, which are arranged in pairs; and b) a bridge circuit having at least four resistance elements ( 1 , 2 , 3 , 4 ), which are associated with the antenna elements ( 11 , 12 , 13 , 14 ) or antenna element pairs; c) with each antenna element pair having at least one associated resistance element ( 1 , 2 , 3 , 4 ) whose resistance value is dependent on the field strength and on the direction of the magnetic field, and which resistance element ( 1 , 2 , 3 , 4 ) is arranged in a field area ( 19 ) which extends between the two antenna elements ( 11 , 12 , 13 , 14 ) of the antenna element pair.