This paper presents a high isolation microstrip diplexer. The lowpass filter based on defected ground structure (DGS) is introduced into the dual behavior resonator(DBR) microstrip bandpass filter. The slow-wave characteristic of EX3S can balance the phase-velocity difference between even-mode and odd-mode of DBR filter, so the rejection in the up stop band of filter can be improved.The DBR filer based on DGS has been analyzed.On this basis, a C-band microstrip diplexer has been developped, and the simulation and experimental result indicate that the insertion loss is less than 1.3dB and the isolation is better than 65dB.%提出了一种高隔离度的微带双工器结构.在微带双重行为谐振(DBR)滤波器中引入基于缺陷地结构(DGS)的低通滤波器,利用DGS的慢波特性减小DBR滤波器奇偶模之间的相速差,从而改善滤波器的上阻带特性.使用本文提出的微带滤波器结构设计并研制了-C波段的微带双工器,仿真和测试结果表明:微带双工器的插入损耗小于1.3dB,隔离度大于65dB.
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