ON THE MICROWAVE LOSS OF GRANULAR HIGH-TC SUPERCONDUCTORS IN THE 0.1 GHZ TO 1 THZ REGION.
P ROY SOC LOND A MAT
555 - 570.
The microwave loss of granular high T(c) superconductors in the 0.1 GHz to 1 THz region is studied, using an effective medium theory previously developed by us, that includes generalization of classical Mie scattering theory for spherical superconductor grains and an improvement due to electromagnetic coupling of the latter. As an illustration of the theory, we have made calculations for a typical granular YBa2Cu3O7-delta material, in the low impurities fraction (c(P)) limit, for dielectric inclusions (voids) and normal metallic inclusions of the (non-superconducting) host material. Our results show that the loss for high quality granular thin films (HQTF) in this limit is independent of c(P), except for an absolutely small value that is technologically unachievable. In view of the substrate losses and other considerations to be discussed, this suggests that the current HQTF performance is unlikely to be significantly superseded. Based on these findings, we confirm that for HQTF, the millimetre band (ca. 100 GHz) and for bulk granular materials, the X band (ca. 10 GHz), are likely to remain the highest frequency regions which are attractive for microwave applications, in accord with recent experiments.
|Title:||ON THE MICROWAVE LOSS OF GRANULAR HIGH-TC SUPERCONDUCTORS IN THE 0.1 GHZ TO 1 THZ REGION|
|Keywords:||MICROSCOPICALLY INHOMOGENEOUS MATERIALS, THIN-FILMS, PROPAGATION, MEDIA, MODEL|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology|
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