A device for compensating field disruptions in magnetic fields of
electromagnets with high field homogeneity, in particular, for
stabilizing the H0 field of an MR measuring system, comprising at least
one field detector (31) for detecting interfering signals (U.sub.in), at
least one control loop for processing the detected interfering signals
(U.sub.in), and at least one compensation coil (34) to which the detected
and processed interfering output signals (U.sub.out) are transferred and
which generates a correction field for compensating the interfering
signals (U.sub.in), is characterized in that at least one of the control
loops comprises a multi-selective filter system (35) which comprises one
or more parallel connected selective filter elements whose center
frequencies can be tuned either once or in an adaptive fashion to the
frequency values of the interfering signals (U.sub.in) to be compensated
for, wherein the outputs of these filter elements are connected to at
least one of the compensation coils (34). The inventive device permits
selective detection of periodic field disturbances with high frequency
components while a major part of the existing noise is faded out, thereby
increasing the SINO.