Enlarging the operating frequency band of 0-dB directional couplers by using branch-line structures of a special type is discussed. Analysis of the basic configuration by the even-odd mode decomposition technique is performed. An experimental verification is presented. INTRODUCTIONRealization of crossovers is a particular problem in the design of microwave integrated circuits. In many cases, when a high isolation between crossing strips is required in a rather large frequency band, it is preferable to avoid a trivial separation of the strips by a dielectric layer. Moreover, it cannot be sometimes realized due to technological reasons. For example, the technological process of fabrication of hightemperature superconducting planar circuits does not provide layered structures, such as superconductor-dielectric-superconductor .It is well known that a single-layer analog of the crossover is the 0-dB forward-coupled directional coupler @C) [l], [2]. The branch-line configurations are of main practical interest for this purpose. Different versions of 0-dB branch-line DC are known. The three-branch DC ( Fig.1-a)

No abstract

Thermal destruction of the superconducting state has been investigated in the HTS bridge with given discontinuity. Temperature distribution and current amplitude distribution have been modeled along the bridge. Modeling has been done taking into account the dependence of the critical current density on temperature. The temperature distribution and the current amplitude distribution in case of the thermal destruction have been obtained at different input power levels. Analysis of the results has shown the influence of the thermal destruction on the current distribution in the bridge and the transmission coefficient 21 .

No abstract