抄録
The fundamental properties of a single layer type microwave absorber using the Bi-system superconductors for the X band (8-12.5 GHz) have been examined. The samples were prepared by crushing the Bi(Pb)-2223 superconductors exhibiting Tc(end)=93.4 K into powders ( < 50 μm) and mixing with the epoxy resin at different ratios from 0 to 50 vol%. The complex reflective intensities of samples were measured by using a vector network analyzer in frequency range from 8.8 to 10.4 GHz at room temperature (300 K) and at liquid nitrogen temperature (77 K). The difference of the complex reflective intensity value between the sample and a metal plate was defined as our reflection loss (R.L.). The electromagnetic wave absorption properties were determined from the frequency dependence of the reflection losses. From the measured results, it was found that the electromagnetic wave absorption properties are influenced by the superconductor content of samples and the temperature. At a room temperature, the electromagnetic wave absorption increased with increasing the Bi (Pb)-2223 superconductor system content, which was due to the increase of the complex permittivity. At a liquid nitrogen temperature, the electromagnetic wave absorption decreased because the superconductor system showed superconductivity.
