Abstract: A comb-line filter is disclosed which includes: (a) a top metal plate and a bottom metal plate; (b) a pair of resonators sandwiched between the top and bottom metal plates and in a parallel and spaced relationship with respect to the top and bottom metal plates; (c) a pair of resonator extensions extending from the pair of resonators, respectively, and (d) a pair of capacitor plates provided above and below the pair of resonators, respectively. The pair of capacitor plates and the pair of resonators extensions are grounded so as to provide a double-parallel capacitor groups. The comb-line filter can be constructed such that the ratio of the separation between the two resonators (d2) and the separation between the resonator and the capacitor plate (d1) is above about 3. By doing so, the coupling capacitance can be reduced to 0.1 pF or lower. In a more preferred embodiment, the ratio of d1/d2 is maintained to below 10, and the coupling capacitance will be essentially zero (less than 0.01 pF).

Abstract: A superconducting tape is fabricated with a composition of Bi.sub.1.81 Pb.sub.0.43 Sr.sub.1.71 Ca.sub.2.14 Cu.sub.3 O.sub.x. The powder of composition is filled into a silver tube and the silver tube is processed by rolling or pressing into a thin tape. The thin tape is heat treated and pressed for several times until the superconducting phase is formed to the tape and the thickness of the tape is equal to or less than 0.07 mm. The resulting tape is highly flexible such that it can be bent into an arc with a very small radius of curvature and nonetheless provide high critical current density.

Abstract: A preparation method of bulk YBa.sub.2 Cu.sub.3 O.sub.x superconductors with high transport critical current and critical current density (Jc), wherein x is 7-.delta., obtained by a modified melt-textured growth method. A continuous dc current carrying capacity exceeding 120 A with critical current density, Jc, higher than 37300 A/cm.sup.2 at 77K has been obtained for the prepared superconductor.