;In this thesis, the quad-channel diplexer, quad-band bandpass filter and octa-channel quadplexer are presented. These three circuits are using distributed coupling technique to achieve low loading effect and can obtain many channels without complicated matching network. The multipath stub loaded resonators is designed to have two resonant path, and the resonant frequencies can be easily controlled by tuning length for each resonant path in the multipath stub loaded resonators. The octa-channel quadplexer is composed of two set of multipath stub loaded stepped impedance resonators(SIR) and two set of multipath stub loaded uniform impedance resonators (UIR)with one long distribute input feeding line and four output feeding line. UIR structures and un-matching Q-factor at harmonic frequency were used to suppress harmonic, through which widestopband was achieved. And meanwhile UIR structures has characteristic of reduce the size of circuit. In short, the filters have advantages of compact size, high passband selectivity and high design freedom. As a result, the proposed octa-channel quadplexer occupies an exceedingly small circuit size, i.e., 0.34λg by 0.19λg, while still having good isolation better than 32 dB for each channel.
