  The dependence of the magnetic field strength required for levitation of a
melt textured, single domain YBCO superconductor disc on the frequency of the
current generating the levitating magnetic field has been investigated. The
magnetic field strength is found to be independent of frequency between 10 and
300 Hz. This required field strength is found to be in good experimental and
theoretical[1] agreement with the field strength required to levitate the same
superconductor with a non-oscillating magnetic field. Hysteretic losses within
the superconductor predicted by Bean's critical-state model[2] were also
calculated. The measured data rules out any significant Bean's model effects on
the required levitation field strength within the measured frequency range.
