| Summary: | 碩士 === 國立臺南大學 === 通訊工程研究所 === 95 === This thesis presents a novel compact coplanar-waveguide bandpass filter (CPW-BPF) designed and implemented on commercial substrate. This filter at center frequency f0 of 3.3 GHz has presented almost very good measured characteristics including the narrow bandwidth of 8.7%, two transmission zeros in the passband edge and wide stopband rejection below 2.45 GHz and from 3.8 to 8 GHz. Experimental results of the fabricated filter show a good agreement with the simulated results.
The thesis also presents a novel dual mode bandpass filter (BPF) with improved spurious response. To obtain low insertion loss, the coupling structure using the dual mode resonator and the feeding scheme using coplanar-waveguide (CPW) are constructed on the two sides of a dielectric substrate. A defected ground structure (DGS) is designed on the ground plane of the CPW to achieve the goal of spurious suppression of the filter. The filter has been investigated numerically and experimentally. Measured result shows a good agreement with the simulated analysis.
Furthermore, a compact and high isolation dual-band coplanar-waveguide (CPW) bandpass filter using the interdigital resonator structures is presented for application in (global positioning system, GPS) and IEEE 802.11b (wireless local area networks, WLANs), and it is extended to a tri-band filter. Since the passbands can be tuned individually, the filters have more design freedoms. The interdigital resonator structures are used to generate and control the second and third passband responses. More than one transmission zero between each passband is realized to improve the selectivity of the multi-band filters and to achieve a high isolation higher than 30 dB between passbands. Good agreements between the simulated and measured results demonstrate our proposed structure.
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