Magnetic field sensor, in particular for measuring magnetic noise fields caused by environmental magnetic noise in combination with MRI apparatus, the magnetic field sensor being further provided with field compensation coils assembly and with a compensation circuit driving the field compensation coils assembly to generate a magnetic field compensating the static magnetic field dissipating outside from the static magnetic field generator or from the gantry of the MRI apparatus at the position of the magnetic sensor. A method for operating the magnetic field sensor and a method and a system for compensation magnetic noise caused by environmental noise are also provided. An MRI apparatus is also disclosed comprising such a system and carrying out such a method for compensating magnetic noise fields.

A compensation method for a magnetic field on board a vehicle including the steps carried out by computer and consisting of: for each measuring time T.sub.i, i=1 to N with N>1, collecting the measured values of the 3D magnetic field Hm.sub.i and those of the angles .sub.i and .sub.i, where .sub.i is the pitch of the vehicle .sub.i is the roll of the vehicle; determining a matrix A and a vector B as a function at least of the collected magnetic field values Hm.sub.i and angles .sub.i et .sub.i, i=1 to N, the matrix A representing the soft iron and nonalignment disruptions and the vector B representing the hard iron disruptions; and the method comprising a step for estimating (105) the pair (A,B) minimizing the expression $\underset{i=1N}{.Math.}{(.Math.A\left({\mathrm{Hm}}_i-B\right).Math.-\frac{1}{N}\underset{i=1N}{.Math.}(.Math.A}^{}$

A compensation method for a magnetic field on board a vehicle including the steps carried out by computer and consisting of: for each measuring time T.sub.i, i=1 to N with N>1, collecting the measured values of the 3D magnetic field Hm.sub.i and those of the angles .sub.i and .sub.i, where .sub.i is the pitch of the vehicle .sub.i is the roll of the vehicle; determining a matrix A and a vector B as a function at least of the collected magnetic field values Hm.sub.i and angles .sub.i et .sub.i, i=1 to N, the matrix A representing the soft iron and nonalignment disruptions and the vector B representing the hard iron disruptions; and the method comprising a step for estimating (105) the pair (A,B) minimizing the expression $\underset{i=1N}{.Math.}{(.Math.A\left({\mathrm{Hm}}_i-B\right).Math.-\frac{1}{N}\underset{i=1N}{.Math.}(.Math.A}^{}$

An apparatus comprises a first substrate and two coils supported by the first substrate and arranged next to each other, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils. One or more magnetic field sensing elements are positioned in the area between the coils and configured to detect the reflected magnetic field.

An apparatus comprises a first substrate and two coils supported by the first substrate and arranged next to each other, the coils configured to each generate a magnetic field which produces eddy currents in and a reflected magnetic field from a conductive target, the two coils arranged so their respectively generated magnetic fields substantially cancel each other in an area between the coils. One or more magnetic field sensing elements are positioned in the area between the coils and configured to detect the reflected magnetic field.

A method for compensating magnetic noise in a spatial volume in which two concurrently operating compensation loops are provided comprising: a closed compensation loop for magnetic noise fields outside the spatial volume and inside the electromagnetically environment; an open compensation loop for magnetic noise fields in the spatial volume; said two compensation loops generating each one a magnetic noise compensation field; said two compensation fields concurrently provide for compensation of the magnetic noise field in the spatial volume.

A method for compensating magnetic noise in a spatial volume in which two concurrently operating compensation loops are provided comprising: a closed compensation loop for magnetic noise fields outside the spatial volume and inside the electromagnetically environment; an open compensation loop for magnetic noise fields in the spatial volume; said two compensation loops generating each one a magnetic noise compensation field; said two compensation fields concurrently provide for compensation of the magnetic noise field in the spatial volume.

Apparatus includes a first portion of conductive material having varying response to a generated magnetic field along a length of the conductive material, wherein the first portion of conductive material produces a varying eddy current and a varying reflected magnetic field, in response to the generated magnetic field. The apparatus further includes one or more reference portions of conductive material having a relatively invariable response to the generated magnetic field, wherein the reference portion of conductive material produces a relatively invariable eddy current and a relatively invariable reflected magnetic field in response to the generated magnetic field.

Apparatus includes a first portion of conductive material having varying response to a generated magnetic field along a length of the conductive material, wherein the first portion of conductive material produces a varying eddy current and a varying reflected magnetic field, in response to the generated magnetic field. The apparatus further includes one or more reference portions of conductive material having a relatively invariable response to the generated magnetic field, wherein the reference portion of conductive material produces a relatively invariable eddy current and a relatively invariable reflected magnetic field in response to the generated magnetic field.

A current sensor includes plural bus bars which are each formed rectangular in a cross section, a pair of shield plates that include a magnetic material and are arranged so as to collectively sandwich the plural bus bars therebetween, and plural magnetic detection elements that are each arranged between the bus bars and one of the shield plates. A distance d between a detection position of a magnetic field intensity at an arbitrary one of the magnetic detection elements and a center position in the width direction between one of the bus bars corresponding to the arbitrary magnetic detection element and an other of the bus bars adjacent thereto in the width direction satisfies the following expression: d/w+0.023(w/h)0.36 where a width of the shield plates is w and an interval along a height direction of the shield plates is h.