This paper presents the design of a compact dual‐band bandpass filter (DB‐BPF) with flexible passband frequencies and sharp skirt. A pair of stub loaded stepped‐impedance resonators (SL‐SIRs) together with two different tri‐section stepped‐impedance resonators (TS‐SIRs) constitute this DB‐BPF. The low impedance sections of two SL‐SIRs and one TS‐SIR are realized by ring structure, on the one hand to acquire two independent resonant modes of SL‐SIRs, and on the other hand to let the harmonic mode of TS‐SIR be away from the upper passband. The cross coupling, the canceling effect of mixed electric and magnetic coupling (MEMC), and the virtual ground introduce the TZs, resulting in the sharp skirt property of proposed DB‐BPF. Step‐to‐step design process is given to guide the DB‐BPF design. As an example, a 0.9 / 1.8 GHz DB‐BPF is designed and fabricated. The fabricated sharp skirts DB‐BPF has a compact size of 0.079λ_g × 0.193λ_g, low passband loss of 0.84 / 0.98 dB and high band‐to‐band rejection of better than 40.6 dB.

中文翻译：

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紧凑的双频带带通滤波器，具有灵活的通带频率和交叉耦合以及磁电混合耦合的裙边

本文介绍了一种紧凑的双频带带通滤波器（DB-BPF）的设计，该滤波器具有灵活的通带频率和尖锐的裙边。该DB-BPF由一对短截负载步进阻抗谐振器（SL-SIR）以及两个不同的三节步进阻抗谐振器（TS-SIR）组成。两个SL-SIR和一个TS-SIR的低阻抗部分通过环形结构实现，一方面获取SL-SIR的两个独立谐振模式，另一方面使TS-SIR的谐波模式为远离高通带。交叉耦合，混合的电磁耦合抵消作用（MEMC）和虚拟接地引入了TZ，从而导致了所提出的DB-BPF的裙边特性。给出了分步设计过程以指导DB-BPF设计。例如，0.9 / 1。8 GHz DB‐BPF的设计和制造。制成的锋利裙板DB‐BPF的紧凑尺寸为0.079λ_克 ×0.193λ_克，0.84 /0.98分贝低通带损耗和能带-能带抑制高优于40.6分贝的。