We propose to fabricate and test microwave devices based upon the non-linear voltage current characteristics of Josephson junctions. In particular one and two-hole microwave SQUID (Supercon- ducting Quantum Interference Detectors) devices and planar microwave sensors utilizing the non-linear characteristics of the junction will be fabricated. The junctions will be ion beam milled to tolerances of 100A in order to take advantage of the latest advances in etching techniques. Only planar devices with the electrical ground in the plane of the film will be studied. Laser deposited YBCO films will be used. We will derive fundamental relationships between the critical current, Ic, and resistance, R, and the fabrication parameters of the junction in order to estimate microwave properties in the junctions. In addition to the calculation of D.C. voltage-current characteristics of a junction in the presence of a microwave field, microwave reflection (S11) and transmission (S21) coefficients will be theoretically calculated for the first time. Measured performance of SQUID devices and microwave planar devices will be modeled in terms of the fluxoid dynamics and free energy of the junction or weak links.
