Magnetic Measurements Low-Magnetic Field Cage – This cage uses 3 sets of orthogonal coils to greatly reduce the magnetic field inside the cage (3 orders of magnitude reduction). Each coil set has 5 equally spaced square coils connected in series. In the center of the cage (the hanging thing with the pink paper attached) is a 3-axis fluxgate magnetometer, which measures the magnetic field in the room along three mutually perpendicular axes. The magnetometer is hooked up to an electronic automated field control unit (in the far left corner of the room), which constantly adjusts the current in the coils to produce the exact antipode of the measured field – in affect producing a net zero field inside the cage.