  When used in Electron-Spin Resonance (ESR) measurements, superconducting
thin-film resonators must be precisely oriented relative to the external
magnetic field in order to prevent the trapping of magnetic flux and the
associated degradation of resonator performance. We present a compact design
solution for this problem that allows in-situ control of the orientation of the
resonator at cryogenic temperatures. Tests of the apparatus show that when
proper alignment is achieved, there is almost no hysteresis in the field
dependence of the resonant frequency.
