一种超宽阻带微带低通滤波器的设计

基于传统阶跃阻抗滤波器,提出了一种易于实现的超宽阻带微带低通滤波器改进设计方案。低阻抗线部分采用扇形微带结构,在同等阶数下,该结构的滤波器与传统阶跃阻抗滤波器相比,具有更紧凑的电路结构以及更好的阻带特性。在滤波器末端并联开路短截线,使得阻带增加额外传输陷波点来抑制寄生通带。利用ADS和HFSS仿真软件对滤波器结构进行优化设计,并进行了实物的加工和测试。实测结果表明,通带3 dB 截止频率为2 GHz,通带内0-1.8 GHz 回波损耗大于20 dB,3-20 GHz 频率范围内的阻带抑制能达到25 dB 以上。     

具有高次谐波宽带抑制新型微带发夹滤波器设计

提出了一种新型微带发夹型滤波器,通过在传统发夹滤波器结构之后采用短路短截线与高次谐波四分之一波长开路短截线并联谐振的方法,可在不影响中频信号的前提下,对高次谐波进行有效抑制.同时在开短路支节之间串联一段微带径向短截线,能实现对谐波的宽带抑制.仿真结果表明此滤波器结构紧凑,具有良好的级联特性,在结构和性能上具有较大优势,适用于多种微波通信系统.     

加载倒T形并联枝节的微带低通滤波器设计

针对传统的高低阻抗微带低通滤波器和开路端短截线微带低通滤波器体积较大、过渡带较缓且插入损耗较大的问题,采用高阻抗传输线单元加载并联倒T形枝节方法,构成带阻滤波支路,抑制了寄生通带,减小了滤波器面积。以7阶切比雪夫低通滤波器为例进行了设计和测试。实验结果表明,倒T形并联枝节滤波器截止频率为5.06 GHz,通带内最大插入损耗小于0.95 d B,在5.61~13.6 GHz内阻带抑制超过21 d B,而滤波器的面积比传统的开路端短截线微带低通滤波器减小20%。     

微带滤波器在EHF频段的应用研究

微带滤波器是微波电路中广泛使用的一种滤波器,但在毫米波频段,常规形式的模型和设计会出现性能恶化和无法实现加工等方面的问题。给出了一种利用改进的短截线形式的滤波器模型制作EHF频段带通滤波器的实例,并给出了仿真优化过程和测试结果,证明了该设计方法的正确性,扩展了微带滤波器在毫米波应用的范围。     

新型折叠多模微带带通滤波器设计

文中提出了一种新型的小型化微带带通滤波器设计方案.方案所提微带带通滤波器的基本结构是折叠多模谐振器,该谐振器不仅具有谐振元件的特性,还能作为开路短截线.新型微带带通滤波器能够实现宽频带的通带响应,并在通带内具有较低的插入损耗和良好的阻带匹配特性,且在通带外额外产生了一对传输零点.本文给出了滤波器的等效电路分析和初步设计方案.该滤波器的最大优点在于进一步减小了滤波器尺寸,同时改善了滤波器的衰减极点,其中心频率为5.2 GHz.     

一种新颖U形缺陷地结构宽阻带低通滤波器

提出了一种通过微带短截线来改变U形缺陷地结构(DGS)截止频率的方法.利用微带短截线和一个U形DGS单元设计了一个宽阻带低通滤波器,并提出通过改变微带短截线的长度来控制该低通滤波器的截止频率的方法.通过仿真比较分析了该低通滤波器与文献中利用一个哑铃形DGS单元和低阻抗微带线方法、级联多个U形DGS单元方法设计的低通滤波器的特性.最后,给出了模拟结果和测试结果,验证了所设计的低通滤波器的有效性.     

一种S波段小型宽带微带带通滤波器优化设计

基于并联短截线谐振器与联接线变换器构成的传统微带带通滤波结构,提出了一种工作在S波段的改进型宽带带通滤波器。以三阶结构为例,通过将两侧并联短截线进行弯折,形成耦合线结构;将中间并联短截线进行拆分,变为并联的短路线和开路线,实现了在通带性能基本不变的前提下,获得阻带可调控的传输零点,进而提高过渡带陡峭度。为了进一步抑制阻带,在滤波器两侧级联扇形微带低通滤波结构,改善阻带性能。利用ADS和HFSS仿真软件对滤波器结构进行仿真优化设计,并最终进行了实物加工和测试。实测结果表明,通带内2~4 GHz插入损耗小于0.7 dB,回波损耗大于17 dB,通带外4.6~6.5 GHz 阻带抑制达到20 dB 以上。     

微带径向短截线基于知识的人工神经网络模型

微带径向短截线具有比直微带短截线在更宽的频率范围内实现低阻抗值的优点。本文采用基于知识的人工神经网络模型模拟微带径向短截线的特性,利用已经具有的先验知识减小神经网络输入输出映射关系的复杂程度有效减少了训练样本的数量,本文建立的人工神经网络模型不仅保贸了全波有限元法的准确性,而且具有快速简便的优点。     

新型阶梯阻抗谐振器滤波器的性能研究

对阶梯阻抗谐振器的谐振特性等进行了分析和计算。设计了一种新型缺陷地结构双T形微带带阻滤波器和一种新型缺陷地结构双H形微带带通滤波器,对其滤波性能进行了仿真计算。该文设计的滤波器具有宽带宽,高衰减,结构简单等优点,可供射频电路应用参考。     

新型毫米波微带带通滤波器

介绍了一种新型的加载电容型毫米波微带带通滤波器。对这种滤波器进行了分析,推导出了滤波器中所用谐振单元间的耦合系数。该滤波器通过加载电容而出现慢波效应,使得在不改变电路性能的情况下,减小了电路尺寸。同时由于电路中加载电容形成的慢波效应而出现了带阻效应,因此对谐波有很好的抑制作用。利用高频分析软件CST仿真分析并设计了这种新型的加载电容型毫米波微带带通滤波器,实验结果与设计曲线结果相符。     

一种基于正方环形谐振器的新型宽带带通滤波器

本文设计了一种紧凑型、宽通带、宽阻带的微带带通滤波器。该滤波器的设计是基于带有两个开路调节支节的正方谐振环。基于紧凑性的考虑,改变了传统方环谐振滤波器的馈电点和开路调节支节的位置,以便对谐振环进行折叠处理。这种改变并不影响谐振环的奇偶模特性。在输入和输出端口,通过两个叉指耦合结构对滤波器进行馈电,这种馈电方式增加了滤波器阻带的带宽和抑制度。滤波器的中心频率为4GHz,相对带宽为45％,通带内的回波损耗小于-12dB,群时延小于0．8ns,1-2．9GHz阻带抑制度大于12dB,5．3～7GHz阻带抑制度大于18dB。     

一种小型化宽阻带窄带通滤波器的研究

为实现滤波器设计小型化,降低带通滤波器的高次谐波干扰,结合传统的1/4波长谐振器结构,采用在谐振器微带线上添加开路线的方法,降低高次谐振频点处的插入损耗,消减谐波影响。相比于半波谐振器,1/4波长谐振器能有效地减小滤波器尺寸,此外开路线的添加除具有消减高次谐波作用,同时还能降低基频谐振点,促进设计小型化。通过仿真软件对该方案的验证及网络分析仪的实物测试表明,此方案具有良好效果,能广泛应用于窄带通滤波器小型化及谐波抑制。     

一种小型化宽阻带窄带通滤波器研究

为实现滤波器设计小型化,降低带通滤波器的高次谐波干扰,本文结合传统的1/4波长谐振器结构,采用在谐振器微带线上添加开路线的方法,降低高次谐振频点处的插入损耗,消减谐波影响。相比半波谐振器,1/4波长谐振器能有效地减小滤波器尺寸,此外开路线的添加除具有消减高次谐波作用,同时还能降低基频谐振点,促进设计小型化。通过仿真软件对该方案的验证及网络分析仪的实物测试表明,此方案具有良好效果,能广泛应用于窄带通滤波器小型化及谐波抑制。     

Knowledge-Based Artificial Neural Network Models for Microstrip Radial Stubs

Radial stubs are a superior choice over low characteristic impedance rectangular stubs in terms of providing an accurate localized zero-impedance reference point and maintaining a low input impedance value over a wide frequency range. In this paper, knowledge-based artificial neural networks are used to model the microstrip radial stubs. Using space-mapping technology and Huber optimization make the neural network models for radial stubs decrease the number of training data, improve generalization ability, and reduce the complexity of the neural network topology with respect to the classical neuromodeling approach. The neural networks are developed for design and optimization of radial stubs, which are robust both from the angle of time of computation and accuracy.     

Asymmetric Parallel-Coupled Lines for Notch Implementation in UWB Filters

In this letter, a novel microstrip parallel-coupled line structure with two asymmetric loading stubs is proposed for notched band implementation in ultra-wideband (UWB) bandpass filter (BPF). The rejection band is introduced by adding asymmetric loading stubs to the two outer arms of three parallel-coupled lines. The lengths and the widths of the stubs can control the bandwidth of the notched filter and can set the notched band at a desired frequency. This structure has been applied to a single-stage UWB BPF in order to produce a narrow notched band inside its passband. The design is successfully realized in theory and verified by full-wave electromagnetic simulation and the experiment.     

Microstrip Coupled-Line Lowpass Filter with Wide Stopband for RF/Wireless Systems

We present the design of a compact microstrip lowpass filter with a wide stopband which is up to ten times the cutoff frequency. The filter is based on a coupled-line configuration and shunt open stubs. The open stubs create additional transmission zeros, which are used to extend the stopband of the filter without any additional components or cascaded units. A prototype lowpass filter with a 3 dB cutoff frequency of 0.428 GHz and a 15 dB stopband extended up to 4.77 GHz is fabricated to validate the theoretical predictions.     

Design of stubs loaded SIR filters by reflection coefficient analysis

In this paper, a new method for designing stubs loaded SIR filter is presented. We can calculate the reflection coefficient of stubs loaded resonator directly by converting the admittance to input terminal. This method replaces the transmission matrix and even-mode and odd-mode analysis. Then, genetic algorithm (GA) is applied to search the corresponding electrical parameters, which provides a more effective and intuitive way to design filters. Then, an ultra-wideband bandpass filter using short-stub loaded SIR is realized, which exhibits a good frequency selectivity from 3.1 GHz to 10.4 GHz. In addition, by applying this method, a dual-passband filter with short and open stubs is achieved. It contains two wide bands at 2 GHz and 5.8 GHz, which concerns the frequencies of GPS and WLAN. Meanwhile, the sizes of these filters are further minimized by bend structure. Finally, the filters are manufactured. As a result, the measured results are in good agreement with the calculated ones. These filters exhibit great frequency-selection characteristics: flat passbands and extremely sharp rejections around the passband. So, based on the verifications of the manufactured filters, this method can be widely used in microwave filter design field.     

Uniplanar compact wideband bandstop filter

A uniplanar wideband bandstop filter is proposed using two bent open-end stubs. The proposed filter consists of the bent connecting line of /spl lambda//sub g//2 between two bent /spl lambda//sub g//4 stubs, which results in wideband design with a rejection bandwidth of 90% at 2.05 GHz. Further, the connecting line and stubs have the same characteristic impedance. The proposed filter compared to the conventional one is also more compact. The area of the novel filter is (/spl lambda//sub g//4)/sup 2/ at the center frequency of the stopband, while the area of the filter realized using the nonbent stubs and connecting line is 2(/spl lambda//sub g//4)/sup 2/ for the same stopband characteristics.     

基于枝节加载开环谐振器的带阻滤波器设计

提出了一种具有良好谐波抑制功能的双枝节加载开环谐振器,加载枝节采用均匀阻抗结构,与同尺寸的开环谐振器相比,结构更紧凑,能够更好地抑制寄生模,而且可以达到更低的谐振频率。分析了加载枝节参数对带阻滤波器抑制二次谐波的影响。通过在加载的双枝节间引入集总可变电容,可以使谐振器具备谐波抑制性能的同时,实现中心频率可调的功能。基于双枝节加载环谐振器设计出一种可调带阻滤波器,中心频率可以在900MHz ~2. 65GHz 范围内调节,而且最低寄生阻带能够抑制到8GHz。     

Ultra-Wideband (UWB) Bandpass Filter With Embedded Band Notch Structures

A compact ultra-wideband (UWB) bandpass filter (BPF) with narrow notched (rejection) band in the UWB passband realized on a microstrip line is implemented and presented in this letter for use in wireless communication applications within the unlicensed UWB range set by the Federal Communications Commission (FCC). The filter consists of five short-circuited stubs separated by nonredundant connecting lines in order to exhibit a high selectivity filtering characteristic. The narrow notched (rejection) band was introduced by using a new technique which involves embedding open stubs in the first and last connecting lines in order to reject any undesired existing radio signal which may interfere with the determined UWB passband. The bandwidth of the notched filter can be controlled by adjusting the width of the stubs or the gaps or both. The length of the stubs can be tuned to select a specific frequency for the notched band. The embedded stubs can be used to excite single or double band-reject response. Two UWB BPFs with narrow notched band having a fractional bandwidth (FBW) of about 4.6% and 6.5% were realized theoretically and verified by full-wave EM simulation and the experiment. Excellent agreement between the predicted and measured results was obtained and is demonstrated