Design and Fabrication of a Novel Compact Low-loss Microstrip Diplexer for WCDMA and WiMAX Applications

Abstract In this paper, a novel miniaturized microstrip diplexer using two bandpass filters (BPFs) is designed and fabricated. The filters consist of stub loaded coupled lines. Additional stubs and T-shape feeding structures are added to miniaturize the size of the presented diplexer. With the adopted special structure, low insertion losses and compact size are obtained. The introduced diplexer operates at 2.12 GHz for WCDMA application and 3.94 GHz for WiMAX application. The obtained insertion losses are 0.25 dB at 2.12 GHz and 0.26 dB at 3.94 GHz. A design technique for analyzing the proposed resonator is introduced to tune the resonance frequencies and obtain a compact size. The size of the proposed diplexer is 23.4 × 16.9 mm2 (0.038 λg2). The measurement result of the fabricated diplexer validates the design technique and simulation results.

摘要 本文设计并制备了一款采用两个带通滤波器（bandpass filters, BPFs）的新型小型化微带双工器（microstrip diplexer）。该滤波器采用枝节加载耦合线结构，额外增设枝节与T型馈电结构以缩减所提双工器的尺寸。通过该特殊结构，本双工器可实现低插入损耗与紧凑体积。所提双工器的工作频段分别适配WCDMA应用（2.12 GHz）与WiMAX应用（3.94 GHz），所得插入损耗分别为2.12 GHz处0.25 dB、3.94 GHz处0.26 dB。本文提出一种用于分析所设计谐振器的设计方法，可实现谐振频率调谐并达成紧凑尺寸目标。所提双工器的尺寸为23.4 × 16.9 mm²（0.038 λg²）。所制备双工器的测试结果验证了本文设计方法与仿真结果的有效性。