| Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 98 === Compact microstrip multiplexers with high isolation are proposed in this thesis. The uniform impedance resonator would resonate at its center and harmonic frequency. To achieve high isolation between channels, the filter is design to suppress its harmonics. To qualify the coupling between the feeding line and resonator, the external quality factor and coupling coefficient are extracted. And this basic block filter is used to design multiplexer. The measured isolations amongst channels are over 40 dB. In comparison with the previous work, the proposed multiplexers perform the feature of high-isolation and compact size. Besides, stepped impedance resonator is used to reduce circuit size. In comparison with the one using uniform resonator, the design using stepped impedance resonator shows smaller circuit size and high isolation. The passbands of the above-mentioned multiplexer are designed at arbitrary frequencies. In this thesis, the triplexer whose passbands design at near frequencies is presented. And this proposed triplexer still has a feature of high isolation.
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