频变交叉耦合带通滤波器的耦合矩阵综合研究

综合代表滤波器拓扑结构和特性的耦合矩阵是交叉耦合滤波器设计的重点。提出了一种基于广义特征值的优化综合方法,通过非线性最小二次求解,将耦合矩阵的广义特征值逼近至广义切比雪夫响应多项式传输函数零极值参考点,优化求解出带有频变交叉耦合带通滤波器的耦合矩阵。通过3个数值实例演示了该方法,并验证其有效性。这是对经典带通滤波器耦合矩阵综合方法的补充,为频变交叉耦合滤波器的设计建立了基础。     

频变耦合双通带滤波器的综合方法

为了解决频变耦合双通带滤波器缺少有效综合方法的问题,文中提出一种优化综合方法.该方法首先通过频率变换技术得到滤波器在归一化双通带域内的特征多项式,然后应用经典的耦合矩阵综合方法得到双通带滤波器的全规范耦合矩阵,进而以矩阵的特征值为趋近目标构造目标函数,最后应用梯度优化算法进行优化获得了双通带滤波器的频变耦合矩阵.文中对...     

多工器的综合与设计

介绍了一种通过特征多项式综合多工器耦合系数的方法。该方法在低通原型频域中运用迭代算法计算优化多工器整体及各支路滤波器的特征多项式,综合得出的各支路耦合系数考虑进了多工器其余支路的影响,大幅缩短滤波器优化时间,且各支路滤波器的传输零点位置可根据需要指定。该方法也适用于双工器及三工器的推导。最终利用软件Ansoft Designer,综合设计并检验一个四工器,利用该方法得出的曲线与预期吻合。     

一种X波段同轴双工器设计

在具有有限传输零点的广义Chebyshev带通滤波器的综合理论基础上,根据计算出的耦合矩阵设计滤波器仿真模型,应用电磁仿真软件结合最优化方法,采用群时延拟合法对双工器的尺寸进行优化设计.实物测试结果表明,双工器的插入损耗≤1.5 dB,输入输出电压驻波比≤1.5,带外抑制大于85 dB,得到的实测曲线满足设计要求,论证了该方法的正确性.     

微波双工器电路综合

近年微波滤波器多项式综合技被广泛用于微波滤波器的设计,将此技术由双端口网络推广至三端口网络可以实现微波双工器的综合。根据微波网络技术,可以推导得到微波双工器电路等效y参数与S参数的关系,进而得到微波双工器散射参数s11,s21,s31与两个通道单通带微波滤波器散射参数s11,s21的关系。应用推广后的微波双工器电路综合技术可以实现微波双工器的精确、快速综合。经过对比发现,微波双工器多项式综合结果与微波双工器电路建模仿真响应吻合度很好。     

基于频变耦合结构的波导滤波器设计方法

针对传统波导滤波器设计中没有考虑耦合结构频率特性导致带宽设计较窄问题,提出了一种基于频变耦合结构的波导滤波器设计方法,该方法将耦合结构等效为一个频变的阻抗变换器,通过等效电路变换将变换器频变特性的影响转换为对谐振腔电抗斜率参数的影响。最后,通过一个宽带波导滤波器的设计实例验证了该方法的有效性。     

一种新型圆腔双工器的设计

针对传统结构的圆腔双模双工器体积和安装面较大的缺点,参考H.Ezzeddine提出的紧凑型波导双工器结构,结合圆腔双模滤波器技术和双工器矩阵理论,给出一种紧凑型圆腔双模双工器拓扑结构,用于公共端口为单模谐振腔、通道滤波器为圆腔双模滤波器的双工器设计,减小其体积和安装面。在给出设计方法和步骤的同时,设计了同轴输入输出端口的C频段双工器,将实物样件测试结果和理论仿真结果进行对比分析,表明本文提出的设计方法,在减小圆腔双模双工器体积和安装面的同时,具有较好的电性能,为这类双工器的设计提供了一种新思路。     

Ku波段交叉耦合波导滤波器的精确设计

针对软件优化法设计交叉耦合波导滤波器的耗时性,利用矩形波导设计了Ku波段折叠型交叉耦合滤波器。采用S参数的多项式综合和矩阵消零的方法提取耦合矩阵,设计过程将全波建模和电路模型分析相结合,利用微波CAD软件HFSS分步骤对每个谐振单元及耦合结构进行仿真,以确定其尺寸,避免了对滤波器的软件优化,所得仿真结果与理论值吻合较好。     

广义切比雪夫滤波器综合的统一理论

无线通信系统需要高性能的交叉耦合滤波器.交叉耦合滤波器的综合从给定的传输零点和回波损耗出发,直到得到各腔体之间的耦合系数.该文介绍在同一电路拓扑结构下提取耦合矩阵的统一理论,可同时实现带通和带阻滤波器的综合方法.     

全屏蔽硅基腔体MEMS双工器

基于三维高精度微电子机械系统(MEMS)加工工艺,研究了一种全屏蔽硅基腔体MEMS双工器的设计及制备方案。简要分析了关于平行耦合线滤波器的相关设计原理,采用λ/4平行耦合线设计两通道滤波器,结合T型匹配网络实现双工器的设计。该双工器以双层高阻硅片作为衬底材料,采用MEMS工艺制备接地通孔,以提高双工器的隔离度及电磁兼容特性。设计的双工器发射通道工作频率为9～10 GHz,接收通道工作频率为11～12 GHz,最终制备出尺寸为7 mm×7 mm的双层硅基双工器,发射及接收通道的回波损耗≤-18 dB,两个通道之间的隔离度约为-30 dB。测试结果与仿真结果吻合较好,为硅基MEMS微系统的集成设计提供技术支撑。     

Accurate synthesis of inline prototype filters using cascadedtriplet and quadruplet sections

A general method for designing low-pass prototype networks with cascade inline topology is presented. The generalized Chebyshev characteristic is imposed, allowing an equiripple response in the passband and transmission zeros arbitrarily displaced in the complex plane (symmetry with respect to the imaginary axis is, however, required). A computationally efficient method is employed for evaluating reflection and transmission polynomials, given the transmission zeros; then, the synthesis of a starting coupling matrix is performed using one of the methods available in the literature. The desired inline topology is then assembled by cascading elementary building blocks (triplets and/or quadruplets), following specific rules which assure the feasibility of the structure; finally, the synthesis is performed by applying a multiple similarity transform to the starting coupling matrix (the set of rotation angles is determined by means of an efficient and fast optimization procedure). Examples are reported which validate the proposed synthesis procedure     

A Direct Synthesis Approach for Microwave Filters With a Complex Load and Its Application to Direct Diplexer Design

This paper presents a direct synthesis approach for general Chebyshev filters terminated with a complex load. The new approach is based on the fact that the polynomial functions for synthesizing the filters are composed for any matched loads. By normalizing the polynomial functions with assumed complex matched load impedance by a real reference load impedance using power waves normalization, a set of new polynomial functions for the same filter, but with real load impedance, can be formulated, from which the coupling matrix for the physical filter design can be obtained using a standard direct filter synthesis approach. This new direct synthesis approach can find many applications. A practical application is the direct diplexer design with a realistic junction model being taken into account. With the diplexer design is concerned, a fast-converged iterative scheme is proposed. The effectiveness and the validation of the proposed scheme are demonstrated by two design examples     

Efficient electromagnetic optimization of microwave filters and multiplexers using rational models

A method is presented for the efficient optimization of microwave filters and multiplexers designed from an ideal prototype. The method is based on the estimation of a rational function adjusted to a reduced number of samples of the microwave device response obtained either through electromagnetic analysis or measurements. From this rational function, a circuital network having the previously known topology of the microwave device is synthesized and compared to a circuital network with the desired response but including nonidealities. All of the process of analysis and model extraction can be seen as a model function that relates the physical parameters of the microwave device with the extracted circuital network parameters. Then, the error vector of the circuital parameters is used to generate a correction vector of the physical parameters through an estimation of the inverse of the Jacobian matrix of the complete model function. The Jacobian estimation is updated at each iteration of the optimization process with no need for additional evaluations of the model function. Two numerical examples of the proposed technique corresponding to the synthesis of a filter and a diplexer are presented, demonstrating the increased efficiency of the proposed technique with respect to direct electromagnetic optimization.     

Synthesis of prototype filters with triplet sections starting fromsource and load

Describes a method for synthesizing an inline prototype filter with a triplet section starting from source and/or from load. This topology allows placing one or two transmission zeros without using cross-couplings inside the filter (it is only required to couple the source (or the load) to the first (or the last) two resonators). The proposed method employs the coupling matrix of a generic prototype, obtained through well-established procedures; then, the coupling matrix of the desired inline topology is determined with a procedure based on multiple matrix rotations (similarity transforms) and numerical optimization     

Synthesis of Resonator Filters With Arbitrary Topology Using Hybrid Method

This paper presents a new synthesis method for resonator filters of arbitrary topology using an evolutionary hybrid method. This method consists of a Levenberg-Marquardt algorithm for a local optimizer and genetic algorithm for a global optimizer, respectively. Unlike the conventional hybrid method in which the local optimization is performed after finding appropriate initial values from global optimization, the local optimizer in the proposed method is used as a genetic-algorithm operator to prevent trapping in local minima of the cost function. This method can provide fast convergence and good accuracy to find the final solution from initial population generated by a random number and the known value for the filters with stringent requirements. In addition, multiple coupling matrices to meet the given requirement can be obtained from the initial population based on a random number. Resonator filters with asymmetric eight-pole configurations for single and dual passbands are synthesized using the current method for validation. Excellent agreement between the response computed from characteristic polynomials and the response computed from couplings is obtained from the proposed method.     

Wide-band waveguide and ridge waveguide T-junctions for diplexerapplications

Scattering parameters of E- and H-plane stepped waveguide and E-plane ridge waveguide stepped T-junctions are obtained using an extension of the three-plane mode matching method. An optimization process is applied to find the T-junctions and step dimensions that yield a low reflection coefficient in one of the T-junctions arms over a wide frequency band. An example of the design of a wideband T-junction diplexer is presented. The diplexer filters are inductive window waveguide filters, and are rigorously modeled using mode matching and a novel two-dimensional curve fitting method, which greatly reduces the CPU time for optimization. The diplexer optimization procedure, as well as the filter modeling method, are described. Experimental results on the optimized T-junction and the diplexer are presented; both show excellent agreement with their computed optimum results, without any adjustments or tuning     

A formulation of the Cauchy method suitable for the synthesis of lossless circuit models of microwave filters from lossy measurements

In this letter, a novel formulation of the Cauchy method is presented, to be employed in the extraction of circuit models from measured(lossy) response of microwave filters. In particular, it is shown how to generate,from lossy measurements, the characteristic polynomials which allow synthesis of a lossless low-pass prototype (and the evaluation of the coupling matrix). To this purpose, suitable constraints are introduced in order to have the transmission zeros generated with the Cauchy method strictly compatible with the low pass synthesis requirements (pure imaginary or complex pair with opposite real part). The application of the proposed method has been verified employing measurements from a test filter for GSM base stations. This method can find application in computer-aided tuning procedures.