The low-frequency electromagnetic response of superconducting plates characterized by strong anisotropy of current-carrying capacity in the plane of the sample is studied experimentally and theoretically. Measurements are made on polycrystalline textured plates of the Y-123 system with the c axis lying in the plane of the sample and on a single crystal with a single preferred direction of twinning boundaries. It is shown that the shape of the curves describing the dependence of the relative losses q on the ac field amplitude h_0 is quite sensitive to the orientation of vector h_0 in the sample plane. As in the case of isotropic samples, the q(h_0) dependence is characterized by a single size peak if vector h_0 is oriented along one of the principal symmetry directions of the anisotropic critical current density. If h_0 deviates considerably from principal directions, two size peaks are observed on the q(h_0) curve. A detailed analysis of the evolution of the q(h_0) curves upon a rotation of vector h_0 in the sample plane is carried out.
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