Critical current-flux (lC-Φ) and voltage-flux (V-Φ) curves of YBa2Cu3Oy junctions and SQUIDS were measured under applied magnetic fields. Ic-Φ curves for single Josephson junctions showed Fraunhofer diffraction pattern. The I-V curves under microwave irradiation showed Shapiro steps. V-Φand Ic-Φ curves for junctions in series were modulated by magnetic fields. Voltage dips were observed for junctions in parallel. The magnetic field period in Ic-Φ curves and V-Φcurves is temperature dependent and it is caused by the temperature dependent X(T).