基于DGS结构的微波滤波器研究与设计

发布时间：2018-05-07 12:18

本文选题：缺陷地结构(DGS) + 等效电路　；参考：《南京邮电大学》2017年硕士论文

【摘要】：缺陷地(Defected Ground Structure,DGS)结构是指在微带线、共面波导等传输线的接地面上蚀刻出特定的缝隙图形,进而改变了传输线的分布电感和分布电容。加载在滤波器上的缺陷地结构可以减少器件尺寸,提高滤波器带外抑制,加之设计方法简单,受到了国内外很多学者的重视。传统哑铃型DGS构成的低通滤波器设计简单,低通段性能良好,但是截止频率处插入损耗矩形系数低,阻带较窄。本文首先分析了哑铃型DGS和等效电路的提取,结合开口环DGS的特点,设计了一款级联开口环DGS单元,增大了DGS等效电容,获得更陡峭的滤波特性。实测数据显示该DGS低通滤波器截止频率为5.39GHz,低通段插入损耗小于0.6dB;带隙在600MHz,-20dB阻带带宽可到6.7GHz。在带通滤波器中,加载的DGS结构可以提供频率调整和耦合补偿等作用。首先根据性能指标设计了一款五阶开口环带通滤波器,分析了该滤波器尺寸变化后的性能变化。在开口环谐振器下方刻蚀相应的DGS结构,滤波器的上下限截止频率都向低频偏移了200MHz左右,通带带宽拓宽到500MHz。测试结果显示DGS带通滤波器和初始尺寸开口环滤波器的传输特性基本一致。最后基于级联DGS滤波器结构对柔性滤波器的弯曲特性进行仿真分析和加工测试。测试了DGS低通滤波器平直状态和弯曲状态下的传输特性,并与仿真结果对比,发现滤波器的弯曲状态对截止频率和阻带抑制都有影响,频偏在25MHz左右。
[Abstract]:Defected Ground structure (DGs) structure is a kind of special slot pattern etched on the ground of transmission lines, such as microstrip lines and coplanar waveguides, which changes the distributed inductance and capacitance of transmission lines. The defective ground structure loaded on the filter can reduce the device size, improve the out-of-band suppression of the filter, and the design method is simple, which has been paid attention to by many scholars at home and abroad. The conventional dumbbell DGS low pass filter has simple design and good low pass performance, but the insertion loss rectangle coefficient is low and the stopband is narrow at cutoff frequency. In this paper, the extraction of dumbbell type DGS and equivalent circuit is analyzed, and a cascade open loop DGS unit is designed according to the characteristics of open loop DGS, which increases the equivalent capacitance of DGS and obtains more steep filtering characteristics. The measured data show that the cut-off frequency of the DGS low pass filter is 5.39 GHz, the insertion loss of the low pass band is less than 0.6 dB, and the band gap is 6.7 GHz at 600MHz / 20dB stopband bandwidth. In the band-pass filter, the loaded DGS structure can provide frequency adjustment and coupling compensation. First, a fifth order open loop bandpass filter is designed according to the performance index, and the performance of the filter is analyzed after the size of the filter changes. The corresponding DGS structure is etched under the open ring resonator. The upper and lower cutoff frequencies of the filter are shifted to the low frequency 200MHz and the passband bandwidth is widened to 500 MHz. The test results show that the transmission characteristics of DGS bandpass filter and initial size open loop filter are basically the same. Finally, the bending characteristics of flexible filter are simulated and tested based on cascaded DGS filter structure. The transmission characteristics of DGS lowpass filter in flat state and bending state are tested. Compared with the simulation results, it is found that the bending state of the filter has an effect on both cut-off frequency and stopband suppression, and the frequency offset is about 25MHz.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN713

【参考文献】