This paper presents a unique structure of a dual-band microstrip bandpass filter (BPF) that works at 1.25 GHz, 1.9 GHz for global positioning systems (GPS) and TV broadcast auxiliary service applications, respectively. The proposed BPF provides compactness, small fractional bandwidth (FBW), small frequency separation, and low IL. The prospective filter is constructed employing broadside-coupling techniques to achieve low insertion loss (IL). The feeding structure is accomplished utilizing a 50 Ω co-planar waveguide (CPW) scheme due to its low loss characteristics. The small 3-dB FBW is accomplished by inserting four transmission zeros (TZs). The size of the overall structure, including I/O transmission lines, is 34.9 × 23.5 mm². The measured and simulated results fit well with each other and show an IL of 0.77 dB and 0.5 dB, and FBW of 7.6% and 8.4% at 1.25 GHz and 1.9 GHz, respectively.

本文介绍了一种双频微带带通滤波器 (BPF) 的独特结构，该滤波器在 1.25 GHz 和 1.9 GHz 频率下分别适用于全球定位系统 (GPS) 和电视广播辅助服务应用。所提出的 BPF 提供了紧凑性、小分数带宽 (FBW)、小频率分离和低 IL。预期滤波器采用宽边耦合技术构建，以实现低插入损耗 ( IL )。由于其低损耗特性，馈电结构是利用 50 Ω 共面波导 (CPW) 方案实现的。小 3-dB FBW 是通过插入四个传输零点 (TZ) 来实现的。包括 I/O 传输线在内的整体结构尺寸为 34.9 × 23.5 mm ². 测量结果和仿真结果相互吻合，在 1.25 GHz 和 1.9 GHz 下，IL 分别为 0.77 dB 和 0.5 dB，FBW 分别为 7.6% 和 8.4%。