| Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 99 === The applications of the multiple-mode resonators are presented in this thesis. With the multiple-mode resonators characteristics, the multiple-mode resonator can be designed in quad-band bandpass filter and compact sharp-rejection broadband bandpass filter with a wide stopband.
The quad-band bandpass filter by splitting half-wavelength resonator with eighth-wavelength stub-loaded resonator is presented. The split half-wavelength resonator can improve the freedom of the external quality factor of each passband. The configuration of the quad-band bandpass filter can be determined from odd- and even-mode excitative path. Moreover, the transmission zeros on both sides of the passband, which can greatly improve the selectivity of quad-band bandpass filter. The core circuit size is 0.09λg2 at the center frequency.
In addition, a compact sharp-rejection broadband bandpass filter with a wide stopband is also presented. The major building block of the proposed filter is a half-wavelength resonator loaded by a meandering coupled line. The loaded resonator could provide three transmission poles in the passband and two transmission zeros beside the passband. By adjusting the dimensions of the meandering coupled line and using multi-path cancellation technique, one can control multiple transmission zeros for a wide stopband. From 2.3 to 4.1GHz, the measured return loss is greater than 15 dB, and the measured insertion loss is less than 0.8 dB. The maximum group delay variation is 0.8 ns, and the core circuit size is 0.05λg2 at the center frequency. For the upper stopband performance, the rejection level is greater than 20 dB from 4.3 to 10 GHz.
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