基于悬置微带的Ku波段发阻滤波器设计

Design of Ku-band Transmit Reject Filter Based on Suspended Substrate Stripline

针对Ku波段甚小终端卫星通信射频系统中发阻滤波器的应用需求,文中采用悬置微带线设计了一款具有陡峭截止特性的伪椭圆低通滤波器。该滤波器由多个T型结级联构成,通过优化设计T型结的结构参数可获得优异的截止特性。为了便于仿真设计,文中对悬置微带T型结的结构进行了详细分析并给出了相应的等效电路模型,在此基础上给出了所提出的发阻滤波器的集总参数模型。通过该集总参数模型可获得分布电路结构的初始参数,有效提高了优化设计效率。为了验证所提出的滤波器性能,利用该结构设计了两款Ku波段发阻滤波器。测试结果表明,两款发阻滤波器的带内损耗分别小于0.3 dB和0.4 dB,带外抑制分别大于33 dB和38 dB,过渡带的衰减斜率可达120 dB/GHz。

In this paper,a quasi-elliptic low-pass filter with steep cut-off characteristics using suspended substrate stripline is designed to meet the application requirements of transmit reject filter(TRF)in radio frequency system of Ku-band very small aperture terminal satellite communication.The filter is composed of multiple cascaded T-junctions and provided with excellent cut-off characteristics,which is obtained by optimizing the connection parameters of T-junctions.In order to simplify the requirements of simulation and design,the suspended stripline T-junction structure is analyzed in detail and the equivalent circuit model is given.Based on it,the lumped parameter model of the low-pass filter is proposed.Then,the initial parameters of the distributed circuit structure can be obtained,which effectively improves the optimization design efficiency.In order to validate the performance of the proposed filter,two low-pass filters for Ku-band TRF application are designed.Measurement result shows that insertion loss of the designed filters is less than 0.3 dB and 0.4 dB respectively,the out of band rejection is better than 33 dB and 38 dB,and the attenuation slope of the transition band can reach 120 dB/GHz.