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Summary: This paper proposes a wideband quasi‐reflectionless bandpass filter with high‐selectivity based on signal‐interference method. The bandpass filter is composed of a bandpass section and two absorptive sections, which consist of a quarter‐wavelength coupled line and signal‐interfering/resistively loaded path, respectively. The bandpass section mainly performs bandpass filtering characteristics while the absorptive sections are applied to consume the reflected signals. By virtue of rationally setting electric lengths and characteristic impedances of the absorptive section to form signal interference, signal dissipation within a wider frequency range and higher selectivity can be realized. Finally, the quasi‐reflectionless bandpass filter was designed and demonstrated with well‐matched measurement and simulation results. Compared with conventional works, the proposed bandpass filter can simultaneously attain wideband, high‐selectivity, and two‐port quasi‐reflectionless performance within a single‐layer topology and well‐integrated structure owing to the signal‐interference technology. The proposed technique may be extensively applied in the RF front‐end and decreases the effect on the stability of communication systems caused by reflected signal. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a high‐selective crossover with a third‐order filtering characteristic, high passband isolation, and multiple controllable transmission zeros based on a coupled topology using single‐ and dual‐mode resonators. By virtue of the odd‐ and even‐mode feature of the stub‐loaded dual‐mode ring resonator, not only can the two resonant modes for different passbands be relatively independently controlled, but also better isolation can be achieved. With a single‐mode resonator and stub‐loaded dual‐mode resonant coupling topology, the resultant crossover can perform third‐order filtering performance in two distinct passbands/channels and generate several transmission zeros outside the desired bands to improve the isolation between the passbands. Experimental results demonstrate that, compared with conventional works, the filtering order of the proposed crossover is promoted and its passband isolation can be significantly improved by about 8 dB. The proposed work may facilitate its widespread applications in high‐performance multichannel integrated microwave systems for avoiding interference between multiple intersecting signal paths. [ABSTRACT FROM AUTHOR]