| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 90 === Filter is an essential component in communication system. It is always implemented by distributed elements at micro- and millimeter- wave frequencies, and distributed elements are usually made by microstrip-line and coplanar-waveguide because of their planar characteristics which make them easy to connect with other circuit components. In this study, various microstrip and coplanar-waveguide filters will be implemented, together with the designs in accordance with their features.
The conventional quarter-wavelength edge-coupled filter will be modified, and the notch performance will also be improved. The area of modified filter is the same compared with the conventional ones, the notch characteristic becomes better at both high and low frequencies, and the insertion loss is also the same. The bandpass filters with center frequencies at 28GHz and 38GHz can be achieved by this structure.
A broadband coplanar-waveguide filter will be proposed based on the novel shunt short stubs and series open stubs. Completely different from the conventional filters, the shunt stubs of proposed filter are located at center main CPW, and the series stubs are located at two ground planes of CPW. The proposed filter has less bound wire compared with the conventional one, so that the cost of fabrication can be reduced.
The two proposed planar filters are both easy to fabricate and compact, they are suitable for communication systems.
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