釔鋇銅氧高溫超導薄膜之微波特性研究

Abstract

在此論文中,主要是探討一包含高溫超導薄膜,損耗性介電基板與金接地結 構之微波等效表面阻抗.我們除了以傳統二流體模型來理論模擬超導層外, 並將介電基板對微波吸收及金有限之電導率都納入考慮.關於該結構對於 平面波之散射情況,在某些特定之條件下,基板共振現象將會發生且整個結 構將變成具損耗之共振器.所有影響此共振現象之因素均被探究.至於微波 量測方面,我們製造了單面超導之環型共振器並加以量測;結果顯示在 79K 下之品質因子約為2400. We have calculated the microwave effective surface impedance for a structure composed of a superconducting thin film, a lossy dielectric substrate and a gold ground layer.While the classical two-fluid model is used for the superconductor, the absorption of the dielectric substrate and the conductivity of the gold ground plane are included in the analysis.In the scattering of plane wave by such a structure, substrate resonance can occur and the structure will act as a lossy resonant circuit under certain conditions.We have also investigated all the factors that influence the substrate resonance phenomenon.As for the microwave measurement, we have fabricated a single-sided YBCO ring resonator and tested its performance.Results revealed that measured Q was around 2400 at 79K.