To develop high-quality rf components for wireless telecommunications, we have processed single-domain YBCO of various dimensions and geometry for the device applications including high-Q resonators and filters. In this development, a critical parameter, the surface resistance, R_s, of single-domain YBCO has been measured in wide ranges of temperature and magnetic field. We have found that the Pippard model can best describe the well oxygenated crystal, indicating the high-quality of single-domain YBCO. However, such scaling breaks down when the oxygen structural disorders are introduced into the sample. A fundamentally different scaling behaviour is observed, which is closely related to the structural defects of oxygen. We report such a behaviour and discuss the possible underlying mechanism.