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System to reduce magnetic fields
Reducing magnetic fields in the 0 Hz range can in some cases be solved with magnetic shielding, cages, Mu-ferro HD. Generally speaking an expensive solution.
For the low-frequency fields in the 10-500 Hertz frequency range, in some cases, we can do this with active compensation. We do this with correction coils around the area where the magnetic field has to be corrected. These coils are quite big in size, about 5 times the length of the correction area. This is to create a homogeneous field where the gradient is nearly equal everywhere.
Near to the sensor, the reduction factor can even be up to 100 times, depending on the homogeneity of the field. The geometry of the correction coils has an influence on the results too.
Generally speaking, this is not the ideal system for EMG and ECG rooms, due to high cost and higher energy consumption. We can tune the system on specific frequencies.
To prevent instabilities we always recommend to combine this with passive shielding.
Zero hertz and low frequencies we can create a contra-field so that the measured field is compensated to prevent you get instability it is wishful to make this in combination with a shield.
Up-to 50000x reduction possible. depending on demand, shape, source and compensation volume.