多层介质频率选择表面的等效电路分析方法

基于数值仿真计算和微波网络理论,提出了一种多层介质中频率选择表面(FSS)等效电路的分析方法.该方法物理过程直观,计算量小,适用于二维任意形状FSS等效电路的精确求解.以方形贴片型FSS为例验证了等效电路模型的准确性,并分析了多层介质对其等效电路参数的影响规律.最后,基于滤波器理论与FSS等效电路模型设计了双层带通型FSS,计算结果表明全波仿真结果与理论计算结果基本一致,为多层FSS的综合设计提供了一种精确设计方法.     

基于滤波器电路设计多层带通频率选择表面

针对传统多层频率选择表面（frequency selective surface，FSS）的设计存在计算量大、耗时长等问题，提出了一种基于滤波器理论和FSS等效电路设计多层FSS的方法.该方法先由滤波器理论综合得到多层FSS的等效电路，再利用FSS等效电路的反演方法将其电路模型转换成多层FSS的结构参数.物理过程简单直观，可以实现任意层数的高阶FSS的快速精确设计.为了验证该方法的准确性，完成了一种K波段带通型三阶FSS天线罩设计以及实物样件加工、测试.测试结果表明该天线罩的传输曲线与滤波器理论设计结果基本一致，且对天线辐射方向图的影响较小，为多层FSS的精确设计提供了一种精确理论设计方法.     

基于集总电阻的S波段小型化超材料吸波器

提出了一种基于集总电阻的S波段小型化超材料吸波器(Metamaterial Absorber,简称MMA)结构, 并进行了理论分析和仿真验证。设计的MMA 基本单元结构由加载了集总元件的电谐振器、中间隔离层和金属背板组成。利用S 参数反演算法求出等效阻抗,结果表明集总电阻的加入使该MMA 在较宽频带范围内有较好的阻抗匹配特性。根据等效电路理论,分析了MMA谐振吸收频率与其单元结构几何参数之间的关系。通过MMA 单元结构表面电流和能流分布分析了其吸波机制。不同模式下的极化角和斜入射角吸收率表明:该MMA具有极化不敏感和宽入射角特性。进一步研究MMA 结构-参数对其吸波性能的影响,通过单元结构几何参数和集总参数的调节获得最优的MMA模型。最终,通过MMA基本单元结构的进一步优化设计,使其在1.9～6.0GHz 范围内吸收率达到90%以上,对应的相对带宽达到101.9%。该设计有望在电磁能量捕获及隐身领域拥有潜在应用价值。     

频率选择表面等效电路的计算与分析

提出一种利用全波数值计算和等效电路理论反演介质中频率选择表面(FSS)等效电路的方法。该方法物理过程直观,适用于任意形状FSS等效电路的精确求解。采用经典方环型FSS,验证该等效电路提取方法的可行性。最后采用该方法研究圆形缝隙型FSS结构尺寸、介质材料以及电磁波入射角对其等效电路参数的影响规律,为后续FSS等效电路研究及快速设计奠定理论基础。     

方环可调频率选择表面吸收体

讨论了带金属导电背板的可调频率选择表面(FSS)吸收体,这种FSS吸收体的阻抗层是无损耗的,集总器件被对称加载到FSS周期单元上.FSS周期单元的谐振频率在特定的频带内会随着集总器件电阻值的改变而发生平移,反射损耗低于-20dB的可调带宽可以覆盖6～12GHz,而且该吸收体的反射、传输特性基本不受入射波入射角度的影响.人射波经过FSS吸收体后基本被消除,而且吸收体的厚度要比传统FSS吸收体薄得多.     

一种X波段小型化可调谐FSS设计

频率选择表面（frequency selective surface,FSS）的研究中,小型化设计一直是研究的热点内容之一,小型化单元结构可以很好地增加FSS的稳定性.文章利用液晶材料给出一种基于三层互耦结构的可调谐FSS单元的设计,为了将每个单元的金属结构连接起来,添加了集总元件来馈电.结果表明,该结构单元尺寸相当于工作波长的1/16,连续可调谐范围可达11.3%.本文所设计结构具有小型化和可调谐的特性,为FSS的设计提供了新的设计思路,具有一定的理论指导意义和实用价值.     

一种具有准椭圆滤波特性的波导型FSS 研究

针对传统二维频率选择表面(FSS)滤波特性差、功率容量不高等局限，结合FSS 设计方法及微波电路基础理论，提 出了一种具有准椭圆滤波特性的波导型FSS 结构。通过理论分析及全波仿真，详细分析了其工作机理。关于结构参数、结构 形式、单元排布方式等对其特性影响的研究，有效地验证了理论分析，同时对其设计具有重要指导意义。结果表明，这种新 型波导型FSS 具有带宽宽、滤波特性好、结构简单、设计便捷、调节灵活等优点，对于FSS 的设计及电磁脉冲防护等研究具 有参考意义。     

具有高角度和极化稳定度的频率选择表面

本文设计了一种基于方形螺旋结构的新型FSS 单元,该单元具有中心对称的结构特性。通过谱域分析法和CST 软件仿真,对影响FSS 阻带中心频率的几何参数进行了分析,获得了优化的设计参数。最后的FSS 单元尺寸为工作波长的0.083×0.083,对TE 和TM 波不同角度入射的传输情况进行了仿真,结果表明对于本文设计的FSS 具有较高的极化和角度稳定性。     

低频集总参数环行器的设计分析

本文对低频集总参数环行器的等效电路进行了分析,给出其结阻抗的表达式,计算了结电感和匹配电容,对集总参数环行器的设计过程进行了阐述。     

低频集总参数环行器的设计分析

本文对低频集总参数环行器的等效电路进行了分析，给出其结阻抗的表达式，计算了结电感和匹配电容，对集总参数环行器的设计过程进行了阐述。     

Dual-band bandpass filter based on mixed electric and magnetic coupling of the hybrid quasi-lumped resonator

A novel compact dual-band bandpass filter based on mixed coupling of the hybrid quasi-lumped resonator is proposed. The filter is composed of two independent signal paths, each can generate one passband with two identical hybrid quasi-lumped resonators. The proposal combines the mixed electric and magnetic coupling technology with this novel resonator in the filter design. Analysis of the filter has been done with the equivalent circuit method. To validate the approach, a dual-band bandpass filter operating at 2.4/5.2 GHz has been fabricated. Both passbands were realised with mixed coupling. An additional transmission zero is generated at either passband. Final fabricated filter has good band skirt, low insertion loss and good out-of-band performance. Reasonable agreement is found between the calculated, simulated and measured results. The implementation area is 0.21λ_g × 0.12λ_g.     

High Performance Frequency Selective Surface Using Cascading Substrate Integrated Waveguide Cavities

Frequency selective surface (FSS) using cascading substrate integrated waveguide (SIW) cavity structure is investigated by finite difference frequency domain (FDFD) combined with the domain decomposition method (DDM). Equivalent circuit model and FDFD-DDM full wave simulations were applied for the design and optimization. Numerical results show that the selectivity performance of the FSS can be greatly improved with proper design and optimization, more rapid roll off side band can be reached as the number of cascading SIW cavities increasing. Its performance is still stable with different incidence angles and polarization     

Accurate circuit model of interdigital capacitor and itsapplication to design of new quasi-lumped miniaturized filters withsuppression of harmonic resonance

A general-purpose circuit model of a microstrip interdigital capacitor (IDC) is presented in this paper for use in the design of new quasi-lumped miniaturized filters. This computer-aided-design-oriented model is developed as a versatile admittance π-network with the short-open calibration technique that we have recently proposed for accurate parameter extraction of a circuit from its physical layout. This technique is self-contained in our method of moments, which accounts for frequency dispersion and fringing effects. A J-inverter topology is further conceived to explicitly formulate the coupling behavior of three types of IDC's. This model provides a unique way for the IDC-related circuit synthesis and optimization based on the accurate equivalent-circuit network extracted from the field theory algorithm. It is validated theoretically and experimentally through an example of a line resonator connected with two IDC's. The proposed scheme is used in the design and optimization of new low-loss miniaturized quasilumped integrated circuits, namely, two types of three-pole direct-coupled bandpass filters. Our measured and predicted results show interesting features of the proposed filter structure such as size reduction and suppression of harmonic resonance if the line resonator is attached by series-connected equivalent inductance     

A Miniaturized and Polarization Independent Electromagnetic Shield for C and X-Band Applications

This paper proposes a miniaturized, polarization independent and dual band frequency selective surface (FSS) based electromagnetic shield. A corrugated FSS and zigzag square ring (ZSR) are arranged in back-to-back configuration over single-layered low-profile dielectric. This configuration not only offers shielding for both C and X-band but also achieves stable polarization independent response for these bands. Simulated and measured results verify its 30 dB average shielding over a wide band and 60° polarization independency alongside. More importantly, the equivalent circuit model analysis and analytical parameterization of this dual band configuration is also investigated. The modelling and simulations are in line with measurements that makes it as a potential shield for C and X-band wireless applications including SATCOMs, Microwave filters and many others.

     

一种识别雷达用半集总参数LTCC双工器

介绍了一种基于低温共烧陶瓷(LTCC)工艺研制而成的小型化半集总高隔离度双工器.该双工器由L波段集总参数低通滤波器和X波段阶跃阻抗( SIR)分布参数带通滤波器组成.通过电磁仿真软件的仿真优化,实际加工滤波器的测试结果与软件仿真结果吻合.其中低通滤波器1dB截止频率为1.46GHz,带通滤波器中心频率为8.3GHz,1dB带宽为0.6GHz,通带内插损小于3.5dB,X波段端口对L波段端口隔离度大于60dB.该小型化LTCC双工器已成功应用于某毫米波战场识别系统的T/R组件中.     

基于LC耦合机制调谐设计薄屏宽带频率选择表面

以环形单元为基础设计出一种三屏金属阵列通过两层薄介质级联的频率选择表面(FSS)。建立等效电路模型,根据传输线理论给出金属栅格阵列(感性表面)与间隔的金属方环(容性表面)的近似电容、电感公式,通过调整结构几何参数分析LC 耦合机制,调谐出最优的宽带传输特性。最后,采用PCB 加工工艺制备了FSS 样件并在暗室进行了传输特性测试。得到的测试结果与数值结果一致,结果表明这种频率选择表面对电磁波大角度入射和不同电磁波极化方式都具有稳定的传输特性。     

基于频率选择表面的宽角扫描阵列

设计并加工了一种基于双层频率选择表面(frequency selective surface, FSS)的一维Vivaldi阵列天线.首先采用周期边界条件分析无限大阵列中的单元特性, 利用等效传输线原理和广义散射参数矩阵来设计优化加载在Vivaldi阵列上方的介质宽角匹配层.然后, 在所加载的双层介质匹配层表面直接印制FSS结构使阵列扫描特性得到极大改善.仿真和实测结果表明, 一维Vivaldi阵列中心单元在7~12 GHz的有源驻波比均小于2.5, 在8~10 GHz波束扫描范围能够达到±60°.仿真结果还表明:采用双层FSS结构的Vivaldi阵列与未加载匹配层的Vivaldi阵列相比, 在7~11.5 GHz增益有2~4 dB的提高; 同时在扫描至±60°时, FSS结构的加载使得阵列在对应扫描角下的交叉极化下降了5~10 dB.