不等波纹函数的综合与分析方法及其在微波领域中的应用

将低通原型网络的特征函数扩展为奇次或偶次多项式,将其命名为不等波纹函数。文中讨论了不等波纹函数型低通原型网络的特征,导出综合与分析方法的公式。给出两个应用实例:(综合)设计收、发共用(通信)天线元的带阻式阻抗匹配网络;设计Ku/Ka频段的低通型MEMS移相器。这两个实例均为用不等波纹函数综合与分析方法得到的新型微波器件。     

不等波纹函数低通原型的理论及应用

本文提出不等波纹函数低通原型，并对其理论进行初步探讨。切比雪夫函数及最平坦型巴特活兹函数皆为其特例。文中给出不等波纹函数的几个性质，最后给出两个应用实例，消除耦合环自感部分的影响；抑制高次模的微带圆盘腔带通滤波器。     

微波滤波器相—频特性的不等波纹函数分析方法

本文简单地介绍不等波纹函数和它的综合方法，并对微波滤波器相－频特性的分析方法作了详细的介绍。实际应用表明，理论计算与测量结果相符甚好。     

可精确综合的超宽阻带等波纹微带低通滤波器

利用公比线网络的可综合特性,设计实现了一种具有宽阻带特性和带内等波纹响应的传输线低通滤波器。该滤波器的原始设计以一段具有Z型拓扑的平行耦合线节为核心,在其四个独立端口处对称加载两对开路枝节线。当所有的传输线元件的电长度均相同时,对上述网络加以分析并得到完整的传输函数。利用平移匹配法,可以在满足指定截止频率和波纹系数的约束下,令其传输函数满足一组可调的等波纹响应。最后,利用开路扇形贴片等效低阻抗加载枝节线,完成实物滤波器的制作。测试与仿真结果吻合良好,验证了设计方法的有效性和正确性。     

宽带匹配网络等波纹增益函数的确定

在网络为无耗和半均匀损耗的情况下,本文讨论了宽带匹配网络等波纹增益函数的确定方法.文中的方法对于网络的阶数n为偶数和奇数时均是有效的.     

低通型阻抗匹配网络的计算机辅助设计

本文在推导阻抗匹配网络输入端反射系数极点解析式和分子多项式的基础上，编写了设计任意偶数阶具有Ｂｕｔｔｅｒｗｏｒｔｈ响应和Ｃｈｅｂｙｓｈｅｖ响应阻抗匹配网络的计算机程序，程序用Ｆｏｒｒａｎ语言编写，当输入匹配网络的阶数ｎ＝２ｍ和阻抗变换比ｒ＝Ｒ２／Ｒ１对Ｃｈｅｂｙｓｈｅｖ响应，通带容许的最大波纹αｄＢ，计算机程序输出匹配带宽和匹配网络归一化元件值。     

中波天线调配网络

天线调配网络由阻抗匹配网络、滤波网络和防雷组件组成,常见的阻抗匹配网络有τ型、T型和π型三种。天调网络直接关系到高频信号能否获得最大功率输出,同时对发射机也起一定的保护作用。     

规范正交梯形结构对数域滤波器

提出了一种基于规范正交梯形网络信号流图模拟的对数域滤波器设计方法.能直接对给定的任意高阶传输函数进行综合.用该方法设计了1dB波纹三阶椭圆埘数域低通滤波器.Pspice仿真表明,所设计的滤波器实际频响特性几乎是理想的,而且具有电路结构简单、需要的元件数少、灵敏度低和最优的动态范围等特性.     

PbMoO4声光器件外部阻抗匹配网络的设计

在PbMoO4声光器件的换能器与电源之间插入阻抗匹配网络,对换能器的声能传输损耗有一定的补偿作用.给出了阻抗匹配后换能器损耗的计算公式、匹配电路结构和元件值、能量损耗与频率的关系曲线图,得出合适的阻抗匹配网络可使得PbMoO4声光器件换能器的声能传输损耗降低,3 dB频带宽度增大的结论.利用阻抗匹配网络的这一优点,优化设计了PbMoO4声光器件换能器的结构.     

广义Chebyshev最优滤波器设计

本文论证了等波纹广义Chebyshev函数滤波器的最优化特性,提出了由设计指标得到广义Chebyshev函数的方法,并且引入信号流图非常简便的得到了对应网络的拓扑结构,最终完成滤波器的设计.本文对具有带外传输零点的滤波器设计具有相当重要的意义.     

The Design and Synthesis of a Class of Microwave Bandpass Linear Phase Filters

This paper is concerned with the design procedure and synthesis of a class of microwave bandpass linear phase filters which simultaneously exhibit a maximally flat amplitude and delay response about band center. In the first part of the paper a systematic procedure is developed for the construction of a nonminimum phase transfer function which exhibits a maximally flat delay and maximally flat amplitude characteristic. In the second part, a synthesis procedure is presented for the realization of the general nth-ordered transfer function by a generalized interdigital network. To simplify the design and construction of this filter, typical characteristics for filters of degree n = 3,4,5,6,7 are graphically presented together with a tabular representation of the polynomials which are required to design the filter. Finally, the results of an experimental filter of degree 3 are incorporated to illustrate that this class of nonminimum phase filters may readily be constructed in practice.     

General Synthesis of Quarter-Wave Impedance Transformers

This paper presents the general synthesis of a radio frequency impedance transformer of n quarter-wave steps, given an "insertion loss function" of permissible form. This procedure parallels that of Darlington for lumped constant filters by providing the connection between Collin's canonical form for the insertion loss function and Richards' demonstration that a reactance function may always be realized as a cascade of equal length impedance transformers terminated in either a short or open circuit. In particular, it is shown that insertion loss functions of the form selected by Collin are always realizable with positive characteristic impedances, and that the synthesis procedure, for maximally flat and Tchebycheff performance, involves the solution, at most, of quadratic equations. In addition, this procedure permits the proof of Collin's conjecture that, for his insertion loss function, the resulting reflection coefficients are symmetrical. Finally, closed expressions are given for the coefficients of the input impedance of a given n section transformer in terms of the n characteristic impedances and vice versa.     

Synthesis of FIR lattice structures

The usual procedure for synthesising the Nth order digital FIR transfer function A_N(z) in which the constant term is unity and the coefficient of z^-N is -a_N(N) by a lattice structure fails if a_N(N)=±1. The author is concerned with a solution to this problem. It is known that under this condition. A_N(z) must be linear phase to be realisable by a lattice structure. A synthesis procedure is given for such an A_N(z). For a general nonlinear phase A_N(z) with a_N(N)=±1, an alternative synthesis procedure is also given in terms of parallel lattice structures     

RC active network synthesis using an amplifier†

A new RC active network synthesis procedure for realizing a given open-circuit voltage transfer function is presented. The interconnection of an ideal voltage amplifier of gain greater than unity and two RC sub-networks in a grounded 2-port configuration is considered for this purpose. It is shown that a general rational transfer function of any order can be realized by such a configuration, provided the transfer function does not have zeros on the positive real axis of the s plane. The method compares favourably with other active RC synthesis procedures using a single finite-gain amplifier.     

Elliptic digital filters

A synthesis procedure is given for elliptic digital filters of order 2q, q=1, 2, 3?. The pulse transfer function is obtained in the form of biquadratic products in z?1. An example illustrates how this method is used to synthetise an elliptic digital filter.     

Minimal realization of a symmetric transfer-function matrix using expansion about a general point "a"

A procedure for the minimal realization of symmetric transfer function matrix by its expansion about an arbitrary point "a" is proposed. The procedure results in realizations leading to reciprocal network synthesis.     

Transfer function synthesis using a finite-gain amplifier

An active RC circuit employing a single finite–gain amplifier, one two–port and two ono–ports, has been presented here for the realization of n general voltage transfer function without positive real axis zeros. The comparative merits of the scheme with respect to that proposed by Rao (1969) are that the synthesis procedure is simpler and the number of passive circuit elements required is smaller. The coefficient of realization of the synthesized transfer function can always be made equal to unity with the scheme. A few examples are included to illustrate the synthesis procedure.