Mixed lumped and distributed network applied to superconducting thin-film broadband impedance transforming

In this paper, a detailed analysis of the properties of mixed lumped and distributed (MLD) lossless elements is first carried out. It is found that such networks can be used as extreme impedance transformers between source and load impedances without large variations in wave impedance values. Then, the lossy transformation technique (LTT) is extended to the design of MLD lossy networks. Finally, to exhibit the practical use of the new method, three examples are given for transforming extremely low input impedance of a superconducting device to a 50 Omega microwave system with the MLD networks. The outstanding advantage using this method is that transformers can be made considerably shorter than by common methods and still physically realizable. The length of the building element is reduced from lambda /4 to lambda /16.<>