An analog signal-interference dual-narrowband bandpass filter (BPF) by combining transmission lines and surface-acoustic-wave (SAW) resonators is proposed. The filter is based on three-path transversal filtering sections (TFSs) with two embedded one-port SAW resonators. By cascading the TFSs in-series through transmission lines, passbands with enhanced fractional bandwidths (FBWs) (i.e., larger than the electromechanical coupling coefficient $k_{t}^{2}$ of the employed acoustic-wave resonator) can be realized. For the purpose of validation, a two-stage microstrip dual-narrowband BPF with two passbands located at 868.95 and 916.5 MHz has been designed, fabricated, and characterized. It demonstrated an insertion loss (IL) of 0.89 dB at 868.95 MHz, 1.57 dB at 916.5 MHz and a bandwidth (BW) of 3.2 MHz (FBW $=3.21\,\,k_{t}^{2}$ ) at 868.95 MHz, and 2.3 MHz (FBW $=1.92\,\,k_{t}^{2}$ ) at 916.5 MHz.

中文翻译：

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混合传输线/声表面波谐振器模拟信号干扰双带通滤波器

提出了一种结合传输线和表面声波 (SAW) 谐振器的模拟信号干扰双窄带带通滤波器 (BPF)。该滤波器基于带有两个嵌入式单端口 SAW 谐振器的三路径横向滤波部分 (TFS)。通过传输线串联 TFS，具有增强的分数带宽 (FBW)（即大于机电耦合系数）的通带 $k_{t}^{2}$ 所采用的声波谐振器）可以实现。出于验证的目的，设计、制造和表征了具有两个通带位于 868.95 和 916.5 MHz 的两级微带双窄带 BPF。它展示了在 868.95 MHz 时的插入损耗 (IL) 为 0.89 dB，在 916.5 MHz 时为 1.57 dB，并且带宽 (BW) 为 3.2 MHz (FBW) $=3.21\,\,k_{t}^{2}$ ) 在 868.95 MHz 和 2.3 MHz (FBW $=1.92\,\,k_{t}^{2}$ ) 在 916.5 MHz。