| Summary: | 碩士 === 國立交通大學 === 電信工程研究所 === 100 === In this thesis, we proposed miniaturization bandpass filters (BPFs) design based on complementary split ring resonators (CSRRs) with two different operating frequency. The two BPFs are operated at 2.45 GHz and 1.85 GHz, respectively. The complementary split ring resonator, which is one kind of the meta-material, since it has unique electromagnetic characteristics, therefore there are many academic literatures about CSRRs which are applied on miniaturization of antennas and microwave circuits.
In the first part of this thesis, a BPF is implemented by utilizing CSRRs and microstrip line coupled interdigital-capacitors to realize necessary circuit components. The open stubs are used to improve the selectivity of the higher edge of the passband, and we proposed the equivalent circuit to explain the frequency responses which are affected by the parts of the BPF.
In the last part of this thesis, we use the proposed BPF to design the compact size microstrip diplexer. By simulation and measurement results, the diplexer has good characteristic responses, such as transmission loss (1.1 dB and 1.4 dB),signal suppression (29.6 dB and 41.21 dB),and 3 dB fractional bandwidth (12.85% and 8.91%). Moreover, the diplexer occupy a small area and has the dimensions of 51 mm×29 mm about 0.42λg × 0.2λg.
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