In this paper, a balanced dual‐band bandpass filter (BPF) with high selectivity and low insertion loss performance is presented by employing stub loaded resonators (SLRs) and stepped impedance resonators (SIRs) into balanced microstrip‐slotline (MS) transition structures. The balanced MS transition structures can achieve a wideband common‐mode (CM) suppression which is independent of the differential‐mode (DM) response, significantly simplifying the design procedure. Six varactors are loaded into the resonators to achieve the electrical reconfiguration. The proposed balanced dual‐band BPF can realize quasi‐independently tunable center frequencies and bandwidths. A tuning center frequency from 2.48 to 2.85 GHz and a fractional bandwidth (20.16%‐7.02%) with more than 15 dB return loss and less than 2.36 dB insertion loss are achieved in the first passband. The second passband can realize a tuning center frequency from 3.6 to 3.95 GHz with more than 12 dB return loss and less than 2.38 dB insertion loss. A good agreement between the simulated and measured results is observed.

中文翻译：

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具有准独立控制的中心频率和带宽的可调均衡双频带BPF

本文通过将短负载谐振器（SLR）和阶跃阻抗谐振器（SIR）应用于平衡微带-缝隙线（MS）过渡结构中，提出了一种具有高选择性和低插入损耗性能的平衡双带通滤波器（BPF）。平衡的MS过渡结构可以实现宽带共模（CM）抑制，而这与差模（DM）响应无关，从而大大简化了设计过程。将六个变容二极管装入谐振器以实现电气重新配置。提出的平衡双频带BPF可以实现准独立可调的中心频率和带宽。调谐中心频率为2.48至2.85 GHz，并且具有小带宽（20.16％‐7.02％），回波损耗大于15 dB，小于2。在第一个通带中实现了36 dB的插入损耗。第二个通带可以实现3.6至3.95 GHz的调谐中心频率，回波损耗大于12 dB，插入损耗小于2.38 dB。观察到模拟结果与测量结果之间的良好一致性。