矩形波导E面金属插片滤波器的CAD技术

矩形波导E面金属插片滤波器是毫米波波段的一种重要滤波器形式。利用计算机辅助技术设计矩形波导E面金属插片滤波器,解决了传统矩形波导E面金属插片滤波器设计过程中自动化程度低,需要大量查表的问题,为这种类型滤波器的研制和生产打下了坚实的基础。采用编写的CAD程序完成一个滤波器设计实例,结果表明了用该程序设计E面滤波器的可行性。 更多还原     

Magnetically tunable rectangular waveguide E-plane integratedcircuit filters

A rigorous field theory method is described for the computer-aided design (CAD) of magnetically tunable E-plane metal-insert filters, where the waveguide sections are symmetrically loaded with ferrite slabs, and for large-gap finlines filters on a ferrite substrate. The design method is based on field expansion in suitably normalized eigenmodes which yields directly the modal scattering matrix of all discontinuities. The theory includes both higher-order mode interaction and the finite thickness of the metal inserts. Optimized data are given for magnetically tunable Ku-band metal insert and finline filter examples. The metal-insert type achieves a tuning range of its operating midband from about 14.1 to 15.7 GHz. The theory is verified by measurements     

基于双金属结构的光纤光栅温度不敏感滤波器

为提高光纤陀螺宽谱光源的平均波长稳定性,提出了一种用60μm超短光纤光栅制作带宽11.77 nm温度不敏感滤波器的方法。利用金属材料的热膨胀系数差,设计了双金属温度补偿结构,能够随温度的升高/降低对光纤光栅压缩/拉伸,有效地补偿光纤光栅由热光效应引起的波长变化。在30～60℃的温度范围内,光纤光栅的温度灵敏度系数为0.15 pm/℃,较未补偿前降低了60倍以上。该结构具有较好的温度不敏感性,可作为光源滤波器提高光源的平均波长稳定性并有望用于高精度光纤陀螺。     

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.     

光谱精确可控Sagnac环滤波器及其在ASE光源中的应用

研究了一种结构新颖光谱特性可精确控制的Sagnac环滤波器,这种滤波器通过在传统Sagnac环中插入两段高双折射光纤和一个偏振控制器构成。利用等效光路和传输矩阵法理论研究了该滤波器的滤波特性,研究结果表明,固定两段高双折射光纤参数,仅通过调整偏振控制器的状态,便可精确控制Sagnac环滤波器的滤波光谱特性。将Sagnac环滤波器用于掺铒光纤（EDF）放大的自发辐射（ASE）光源的光谱平坦滤波,通过调节偏振控制器三个波片的倾斜角度,实验获得了光谱平坦的宽带ASE激光。     

FBG光纤传感器的同步探测技术

光纤光栅传感解调系统的波长校准技术是人们关注的焦点,通常是将固定波长的FBG固定在恒温箱中,以此作为光纤光栅传感解调系统的参考元件．此方法占用了宽带光源的某个波长范围,从而制约了解调系统的波长扫描范围．构建的光纤光栅传感解调系统,将FP滤波器的驱动锯齿信号转变为方波信号,以此作为同步处理所需参考信号,省去了这个固定波长的FBG传感器,充分地利用了宽带光源的波长范围,并使得解调技术简单,同时提高了外接FBG传感器的数量．     

Variable Fractional Delay Filter Design Using a Symmetric Window

In this paper a numerically efficient method for designing a nearly optimal variable fractional delay (VFD) filter based on a simple and well-known window method is presented. In the proposed method a single window extracted from the optimal filter with fixed fractional delay (FD) is divided into even and odd part. Subsequently, the odd part is discarded and symmetric even part of the extracted window is used to design a family of nearly optimal filters with varying FD. In addition to window extraction, the proposed approach requires filter gain correction which is dependent on the desired FD. Optimum values of the gain correction factor as well as the extracted window can be computed beforehand, which allows us to design a nearly optimal FD filter with arbitrary FD at low numerical costs during runtime. On the basis of the proposed filter design method, the universal structure of VFD filter allowing for change of filter type and length has been proposed. In the paper, three FD filter optimality criteria are considered, which are maximal flatness, Chebyshev (minimax), and least squares.     

一种新颖的宽带可调光纤光栅滤波器

分析了光纤光栅（FBG）调谐的基本原理,进而采用新颖的调谐结构,设计并实现了一种宽带可调谐的FBG滤波器。该滤波器仅用1支FBG制做而成,其波长调谐范围最高可达40nm。实验结果表明,该FBG滤波器的调谐波长与调谐步进位移量之间具有良好的二次曲线关系。     

基于SISL的介质填充双通带滤波器设计

为实现滤波器的小型化,基于介质集成悬置线(substrate integrated suspended line, SISL)结构提出了一种介质填充双通带滤波器的设计方案. 首先将高介电常数的介质块填充入SISL的空气腔中,提升SISL的等效介电常数,实现电路的小型化,高介电常数介质块可以直接被SISL固定;然后利用T型结连接两组工作在不同频段的滤波器从而使得两个通带相对独立;最后利用仿真软件进行优化,确定介质填充双通带滤波器的尺寸,并进行加工与测试. 仿真与测试结果表明,二者具有较好的一致性,两个通带频率内的回波损耗均优于15 dB,电路的核心尺寸为0.058λ_g×0.139λ_g(λ_g为SISL在第一通带中心频率处的导波波长). 此双通带滤波器具有小尺寸、自封装等优势,且所有层介质基板均采用低成本的FR4板材,降低了制造成本.     

A rigorous cad of millimeter wave bandpass filter with all-metal insert in waveguide

In this paper, a bandpass filter with all-metal insert, an inductive strip in the E-plane of a waveguide is analyzed by a prototype filter and the scattering matrix of the strip is calculated by electromagnetic fields theory theoretically. By means of matrix combining technique, the scattering matrix of a bandpass filter of this type is obtained. And a rigourous error function is used to optimize the CAD program by Powell's method and make the experimental results agree well with the theory design at V-band.     

Synthesis of grating lattice circuits

The realization of high-performance components based on optical infinite impulse response (IIR) filter design theory is desirable for next-generation global optical networks. Previously proposed IIR filter synthesis methods are matrix factorization techniques for a lattice circuit using ring resonators. The size of ring resonator limits the bandwidth of the lattice filters. In this paper, two configurations of grating lattice filters are synthesized by using a scattering matrix representation for the grating. The grating is one of the most powerful optical elements both in fiber optics and photonic integrated circuits. One configuration is a serial grating lattice filter configuration and the other is a parallel grating lattice filter configuration. The actual frequency response of the synthesized grating lattice filter is calculated to show the design limitation due to the frequency response of the element gratings     

Highly compact tunable stop-band active filter for advanced communication systems

In this paper a novel electronically tunable active stop-band filter design is reported. This filter is designed in the UHF band to avoid the degradation of the receiver sensitivity when interfering signals at fixed or changing frequency are coupled to the antenna of the receiver front-end. The presented solution shows low insertion loss far from the notch frequency while rejecting the interfering signals by more than 40 dB regardless of their frequencies. The filter architecture is simple; it is based on a main transmission line segment to which a quarter-wavelength line segment is coupled. The fact of loading the end of the coupled line by a novel tunable active capacitor circuit introduced in this paper allows tuning simultaneously the filter frequency and the band-stop depth while reducing the power consumption and maintaining the device electrically stable. Moreover, by using the semi-lumped approach, the filter is compacted of more than 70 % in comparison to the conventional quarter-wavelength coupled line. The concept is demonstrated using low cost FR4 substrate and surface mount technology. The complete design has been fully simulated and experimental prototypes realized. Measurements are demonstrating the benefits of the proposed design.     

采用复合滤波器的温度可调谐多波长光纤激光器

提出了一种基于复合光纤滤波器的在室温下稳定输出多波长掺铒光纤激光器,该激光器由两个级联球状结构的马赫-增德尔干涉仪（MZI）和一个双折射光纤滤波器-Lyot滤波器组成。球状结构MZI是由光纤熔接机在一段单模光纤（SMF）放电设计而成的。Lyot双折射光纤滤波器是利用一段保偏光纤（PMF）和两个偏振控制器（PC）连接而成,该结构可以诱导非线性偏振旋转效应和双折射光纤效应来抑制模式竞争产生多波长。Lyot滤波器和球状结构的MZI作为模式限制器件,并且Lyot滤波器对级联球状结构MZI的透射谱进行调制,其透射谱周期决定了复合滤波器结构的透射谱周期。在室温下,该系统实现了边模抑制比约为40 dB的九个波长的同时激射,且波长间隔约为0.68 nm,与Lyot滤波器透射谱周期一致。为了验证输出波长的稳定性,在2 h内,每隔10 min观察输出的波长,实验证明,室温下中心波长输出功率的浮动小于0.67 dB。此外,将两个球状结构MZI放置在高温炉上,使其外界温度从30℃升至110℃时,输出波长光谱的调谐范围可达到6.69 nm。     

声表面波窄带梯形滤波器的仿真与设计

使用机电耦合系数小的基片可减小声表面波梯形滤波器的带宽,但会降低基片的声电转换效率,增加滤波器的插入损耗.该文设计了基于m推演结构的梯形滤波器,使滤波器过渡带宽上产生2个额外的传输零点;降低通带宽度,并在此基础上分析了各参数对其性能的影响,通过调整参数以满足不同需求.实验结果表明,中心频率为500 MHz的梯形滤波器,带宽由40 MHz减小到15 MHz,矩形系数由1.6减小到1.3,滤波器的插入损耗增加了0.5 dB.     

Tunable multiwavelength fiber laser employing a comb filter based on a polarization-diversity loop configuration

A tunable multiwavelength fiber laser based on a semiconductor optical amplifier (SOA) is newly proposed. The proposed fiber laser employs a fiber comb filter based on a polarization-diversity loop configuration (PDLC) for the multiwavelength selection. The spectral characteristic of the comb filter is graphically explained by tracing the state of polarization (SOP) of the light propagating through the filter on the Poincare sphere. Particularly, the method of adjusting the filter characteristics is established with the help of the Poincare-sphere representation. The experimental results show that 18 laser lines oscillate with the signal to amplified spontaneous emission noise ratio over 25 dB. Particularly, all of the laser lines with a fixed channel spacing of /spl sim/ 0.8 nm can be continuously shifted by adjusting only a wave plate contained within the filter.     

扇形微带短截线型滤波器的设计

采用扇形微带短截线作为滤波器的基本单元,设计出具有宽频特性的滤波器,在微波平面电路的设计中有着良好的应用前景。通过设计扇形微带短截线单元的物理尺寸,能够实现特定频段的高选择性滤波器。用ADS和HFSS对这种新型滤波器与传统直形滤波器进行了特性对比,在特性方面,新型滤波器比传统滤波器具有更陡峭的过渡带和更宽的频带等优点;在结构方面,新型滤波器电路相对传统滤波器可以减少基板面积。     

传导型电源干扰的抑制

本文以开关电源为例,分析了电源EMI滤波器的等效电路,并介绍了用于抑制电源线电磁干扰的滤波器的插入损耗的计算方法,为电源EMI滤波器的设计提供了参考.     

基于SIW技术的毫米波滤波器研究与设计

基于基片集成波导（substrate integrated waveguide,SIW）结构设计了两款四阶的耦合带通滤波器,使用三维全波电磁场仿真软件HFSS对设计的两款滤波器进行了仿真设计和优化.由仿真结果分析得出,两款滤波器的工作频率均位于毫米波频段.第一款SIW滤波器实现了切比雪夫型响应,中心频率为20 GHz,带宽为2 GHz,通带内的插入损耗低于1.5 dB,回波损耗低于-20 dB,在阻带中对信号的衰减程度可以达到50 dB.第二款SIW滤波器实现了准椭圆函数型的响应,中心频率为29.1 GHz,带宽为300 MHz,通带内的插入损耗低于1 dB,回波损耗低于-20 dB,在通带到阻带的过渡中实现了两个陷波点.仿真结果表明,在毫米波滤波器设计中引入SIW结构,有利于优化滤波器尺寸,得到较好的滤波器性能指标,是毫米波滤波器发展的一个重要方向.     

基于PDMS基片的回音壁模式光纤激光器

介绍了一种基于聚二甲基硅氧烷(PDMS)基片的回音壁模式(WGM)光纤激光器。激光器主要由多模石英光纤、塑料楔形光纤、激光染料溶液、玻璃基底和PDMS基片构成。将一根直径为279μm的石英裸光纤和一根直径为200μm的塑料楔形光纤耦合后固定在一块长和宽分别为2cm和1cm的玻璃基底上,在玻璃基底上浇注PDMS溶液后再经烘干形成厚度约为400μm的柔性PDMS基片。在基片上石英光纤与楔形光纤的耦合位置处刻出一个长为0.4cm,宽和高均为400μm的光纤沟道,在沟道中填入诺丹明6G的乙醇溶液并用另外一块玻璃基片封装后构成基于PDMS基片的回音壁模式光纤激光器芯片。采用沿石英光纤轴向消逝波光抽运方式,在PDMS芯片上实现了抽运能量为8.5μJ的低阈值的回音壁模式激光定向输出。     

0.1 THz鳍线单平衡式基波混频电路研究

研究了一种基于石英基片的0.1 THz频段的鳍线单平衡混频电路,混频电路的射频和本振信号分别从WR10标准波导端口通过波导单面鳍线微带过渡和波导微带探针过渡输入,中频信号通过本振中频双工器输出。这是一种新型的混频电路形式,与传统的W波段混频器相比,混频电路可以省略一个复杂的W波段滤波器,具有电路设计简单、安装方便的特点。该电路使用两只肖特基二极管通过倒装焊工艺粘结在厚度为75 m的石英基片上,石英基片相对传统基板,可以极大提高电路加工精度。在固定50 MHz中频信号时,射频90~110 GHz范围内,0.1 THz混频器单边带变频损耗小于9 dB。