| Summary: | 碩士 === 中原大學 === 電子工程研究所 === 98 === Abstract
In this thesis, we design a low-pass feeding line (LPFL) in a cross-coupled planar microwave filter by using YBa2Cu3O7 (YBCO) high-temperature superconductor (HTS) thin films on the LAO substrate. The microwave filter is based on a quadruplet geometry used to the inner-folded stepped impedance resonator (SIR), and the central frequency is 1.8 GHz. Furthermore, a tap-connection technique by tapping the input microstrip lines with parallel stubs, the LPFL, high-frequency spurious suppression structure, at the skew-symmetrical-feed structure is applied to the microwave filters so as to suppress the upper stopband and meanwhile to enhance the passband characteristics. The experimental results show that the center frequency of 1.78 GHz, return loss better than 15 dB, insertion loss less than 1.2 dB, suppresses the upper stopband above 20 dB. The advantages of the superconducting microwave passband filters such as low insertion loss and sharp band edge skirts will make the microwave filters take the leading position in wireless communication industry.
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