| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 88 === Filter is an importance component in communication system. Filters at microwave frequencies can be realized by transmission lines. Coplanar waveguides (CPW) have some attractive features over microstrip lines. To fully utilize the advantages of CPW, this study carefully examines the coplanar waveguide filter. All the CPW filters reported to date utilize λ/2 orλ/4 open and short stub structures. These filters occupy large area and are not suitable for use in uniplanar MIC/MMIC's. In this study, three compact CPW filters are proposed and carefully examined.
We first examine the broadbandλ/4 CPW bandpass filter; and then, by a modification of theλ/4 open and short stub configurations, a reduced-size broadband CPW filter is proposed. This reduced-size broadband filter is a quarter of the conventional CPW filter.
We next examine the capacitive-coupled half-wave filter, inductive-coupled half-wave filter, and LC-coupled quarter-wave filter which are suitable for narrow-band applications; then, a narrow-band reduced-size CPW bandpass filter structure is propose which is a modified version of the conventional resonator composed of slow-wave configuration. The size of this reduced-size narrow-band filter is 3/5 that of LC-coupled quarter-wave filter.
We finally utilize a series CPW resonator to implement an elliptic CPW low-pass filter. Because of simple fabrication and low loss, these filters are useful in uniplanar MIC/MMIC systems.
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