A Novel Design Method for High Isolated Microstrip Diplexers Without Extra Matching Circuit

IEEE Access

Haiwen Liu¹  Baoping Ren²  Xuehui Guan²  Wang Liu²  Pin Wen³ 

[1] School of Electronics and Information Engineering, Xi&x2019;School of Information Engineering, East China Jiaotong University, Nanchang, China;an Jiaotong University, Xi&x2019;

关键词: Composite resonator;    extra matching circuit;    high isolation;    impedance transformation;    microstrip diplexer;    transmission zeros;   

DOI  :  10.1109/ACCESS.2019.2936553

来源: DOAJ

【 摘 要 】

A novel design method of microstrip diplexer without extra matching circuit is proposed in this paper. Because of the synthesizable circuit parameters and controllable transmission zeros (TZs) in composite resonator (CR) cell, diplexer A based on CR cell is proposed. By allocating TZs at center frequency of the opposite channel, as well as the using of impedance transformations of J inverters, high isolation and good passband selectivity are realized in diplexer A without extra matching circuit. In order to improve the stopband performance, diplexer B based on coupled CR cells is proposed. Furthermore, diplexer B using the proposed design method is implemented by directly combining two bandpass filters (BPFs), which simplifies significantly the design process of diplexers. Diplexer A operated at 1/1.2 GHz and diplexer B operated at 1/1.5 GHz are designed and fabricated. The measured isolation characteristics in diplexer A and diplexer B are all higher than 40 dB. Good agreements between simulated and measured results are achieved, which successfully verifies the proposed design method of diplexers.

【 授权许可】

Unknown