A local coil unit for a magnetic resonance apparatus, which radiates a
radio-frequency field into an examination subject, has a housing and at
least a part of the housing is formed of an insulating dielectric
material that passively compensates for an inhomogeneity in the
high-frequency field in the subject. The material has a relative
dielectric value .epsilon..sub.r of greater than 50, preferably greater
than 100, and a dielectric loss factor tan .delta. of less than
2.5.times.10.sup.-2, preferably less than 1.times.10.sup.-3. In the
dielectric material displacement currents are generated which create an
additional magnetic field that compensates for the minima in the B1 field
as a result of the eddy currents arising in the patient due to the
radio-frequency radiation.
