Wide-Band Equivalent Circuits of Microwave Planar Networks

A broad-band equivalent circuit of a generic microwave planar network is derived in terms of lumped constant elements. Contrary to previously proposed equivalent circuits, whose elements are strongly frequency dependent, the elements of the new one show only a smooth dependence on the frequency, because of the dispersion properties of microstrip structures. The equivalent circuit proposed is therefore easy to handle and is shown to be a useful basis for direct synthesis of planar structures. Good agreement with the theory is demonstrated by experiments performed on structures with different geometries up to 12.5 Ghz, by using equivalent circuits whose elements are assumed to be constant with the frequency.     

自由振动压电振子的一种复参数等效电路

将复数概念引入到等效电路元件参数中,并以自由振动压电振子的一种常用振动模——纵向长度伸缩振动模为例,给出了一种复参数等效电路,并推导了等效电路参数与压电材料参数之间相互关系。等效电路元件参数的虚部表示压电振子机械、介电、及压电损耗。给出了由复参数等效电路模型作出的阻抗圆图与由振动理论给出的阻抗圆图以及由传统模型所作出的阻抗圆图。结果表明,新的复参数模型优于传统模型,是一种精确的等效电路。     

Circuit aspects of transistor parametric frequency doublers

Factors determining the performance of a transistor parametric frequency doubler are considered from the transistor equivalent network viewpoint, emphasising the integral nature of the active and parametric regions. On the basis of a simple transistor model connected as a frequency doubler, it is shown that a higher loading of the harmonic circuit is required than for a conventional varactor multiplier. By use of circuit models which incorporate parasitics inherent in a high-power, high-frequency planar transistor structure, it is shown that more efficient pumping of the varactor region is possible than would be predicted from the standard equivalent circuit models.     

Circulators Using Planar WYE Resonators

An important class of commercial three-port circulator relies for its operation on a junction resonator consisting of the symmetrical connection of three open-circuited transmission lines. A feature of this resonator is that it may be quarter-wave coupled to form a circulator with a moderate specification (25-percent bandwidth to 25-dB return loss points) and physical dimensions of the order of directly coupled conventional circulators (using a disk resonator). For circulators for which the in-phase eigennetwork may be represented by an ideal short-circuit, the equivalent circuit is a one-port network which may be formed from a characterization of the constituent resonator. This feature is used in this paper to study the equivalent circuit of junction circulators using planar WYE resonators. The derivation of the equivalent circuit parameters is supported with the design of a 4-GHz quarter-wave-coupled stripline circulator.     

Equivalent Circuit for Partially Dielectric-Filled Rectangular-Waveguide Junctions

The problem of electromagnetic-wave propagation in junctions between two symmetrically, partially dielectric-filled waveguides was investigated, and the solution is presented in the form of a two-port equivalent circuit, This equivalent circuit includes an ideal 1:1 transformer, which is connected to transmission lines with impedances equal to those of the two waveguides, in cascade with a T network. Elements of the T network and the characteristic wave impedances of these partially dielectric-filled waveguides have been studied, and the results are presented in graphs for different dielectric constants, slab thicknesses, and operating frequencies.     

An electromagnetic-field method modeling of a radial line planar antenna with coupling probes

This communications describes an electromagnetic model of a radial line planar antenna consisting of a radial guide with one central probe and many peripheral probes arranged in concentric circles feeding an array of antenna elements such as patches or wire curls. The model takes into account interactions between the coupling probes while assuming isolation of radiating elements. Based on this model, computer programs are developed to determine equivalent circuit parameters of the feed network and the radiation pattern of the radial line planar antenna. Comparisons are made between the present model and the two-probe model developed earlier by other researchers.     

Ferrite Planar Circuits in Microwave Integrated Circuits

The ferrite planar circuit to be discussed in this paper is a general planar circuit using ferrite substrates magnetized perpendicular to the ground conductors. The main subject of this paper is the analysis of an arbitrarily shaped triplate ferrite planar circuit. In particular, the circuit parameters of the equivalent multiport are determined. To analyze ferrite planar circuits in general, two approaches are possible. One approach is based upon a contour-integral solution of the wave equation. In the other approach the fields in the circuit are expanded in terms of orthonormal eigenfunctions. Examples of the application of such analyses are described.     

New synthesis method for a branch-line 3 dB hybrid: a hybridapproach comprising planar and transmission line circuit concepts

A synthesis method for a stripline-type branch-line 3-dB hybrid which is based on an equivalent circuit derived by the planar circuit approach is presented. The equivalent circuit of an ideal 3-dB hybrid is derived first from those of the segmented circuit elements, i.e., four three-port junctions and four quarter-wave transmission lines. A systematic synthesis process is then developed upon the basis of the equivalent circuit. Practical hybrid circuit having optimized circuit patterns which were constructed for center frequencies of 3, 5, and 7 GHz are discussed. Their measured characteristics are described. The results are shown to agree well with the theory     

厚度伸缩压电陶瓷振子

对厚度伸缩压电陶瓷振子的振动状态进行了分析,并得到其等效电路.推导了振子的谐振频率、反谐振频率以及等效电路参数与振子尺寸、振子材料的介电、压电、弹性常数间的关系式.最后讨论了振子的一些特性和制作.     

Thermal resistance analysis by induced transient (TRAIT) method forpower electronic devices thermal characterization. I. Fundamentals andtheory

In this paper, a careful theoretical analysis of the thermal dynamics of an electronic device and its package was carried out in order to study the problem of the equivalent thermal circuit implementation. It was found that the device temperature evolution in time is ruled by an infinite and convergent series of time constants. The knowledge of the first n terms of the time-constant spectrum obtained from the temperature transient measurements allows the complete characterization of a suitable and reliable equivalent thermal circuit structured as a Cauer low-pass network with n cells. The total thermal resistance is therefore evaluated as a sum of several contributions due to given parts of the whole system. The techniques allowing the physical identifications of these contributions are also discussed. Furthermore, the influence of plastic coverage on the device thermal behavior is taken into account. The proposed characterization method is also applied to one-dimensional (1-D) multilayered simulated structures in order to study the influence of the number of time constants used for the analysis and effects of local defects or modifications of the material thermal properties     

太赫兹平面肖特基二极管参数模型

根据太赫兹平面肖特基二极管物理结构,在理想二极管SPICE参数模型的基础上建立了二极管小信号等效电路模型。依据该二极管等效电路模型设计了基于共面波导（CPW）去嵌方法的二极管S参数在片测试结构,并对其在0.1~50 GHz、75~110 GHz频率范围内进行了高频小信号测试,利用测试结果提取了高频下二极管电路模型中各部分电容、电阻以及电感参数。将相应的高频下电容与电阻参数分别与低频经验公式电容值和直流I-V测试提取的电阻值进行了对比,并利用仿真手段对高频参数模型进行了验证。完整的参数模型以及测试手段相较于理想二极管SPICE模型和传统的参数提取方法可以更为准确地表征器件在高频下的工作状态。该建模思路可用于太赫兹频段非线性电路的优化设计。     

Numerical TRL calibration technique for parameter extraction of planar integrated discontinuities in a deterministic MoM algorithm

In this letter, a thru-reflect-line (TRL) calibration procedure is applied and integrated with a full-wave method-of-moments (MoM) simulator for the parameter extraction of planar discontinuities and circuits. Three TRL calibration standards are numerically formulated and consistently characterized by the MoM simulator. An equivalent circuit model of a circuit discontinuity of interest can then be extracted by calibrating out the erroneous effect of port discontinuity in the deterministic MoM algorithm. As an example, a microstrip open-end circuit is comparatively studied in terms of its equivalent fringing capacitance, and effectiveness of the proposed technique is verified.     

Equivalent circuit modeling of losses and dispersion in single andcoupled lines for microwave and millimeter-wave integrated circuits

Losses and dispersion in open inhomogeneous guided-wave structures such as microstrips and other planar structures at microwave and millimeter-wave frequencies and in MMICs (monolithic microwave integrated circuits) have been modeled with circuits consisting of ideal lumped elements and lossless TEM (transverse electromagnetic) lines. It is shown that, given a propagation structure for which numerical techniques to compute the propagation characteristics are available, an equivalent circuit whose terminal frequency and time-domain properties are the same as the structure can be synthesized. This is accomplished by equating the network functions of the given single or coupled line multiport with that of the model and extracting all the parameters of the equivalent circuit model by using standard parameters identification procedures. This model is valid over a desired frequency range and can be used to help design both analog and digital circuits consisting of these structures and other active and passive elements utilizing standard CAD (computer-aided design) programs. To validate the accuracy and usefulness of the models, results for a mismatched 50-Ω line in alumina and a high-impedance MMIC line stub are included     

基于等效电路模型的Mesh结构P/G网布线优化方法

本文在对供电用串联电阻链的等效电路模型进行详细论证的基础上，根据Mesh结构P／G网所具有的结构特点，将P／G网电阻网络加以等效变换，得到比原网络规模小得多的等效简化网络。然后用现有的布线优化方法来优化简化网络，速度可提高至少一个数量级。     

Analysis of a Network of Electrically Coupled Neurons Producing Rhythmic Activity in the Snail Helisoma Trivolvis

This paper deals with a quantitative analysis of a network of electrically coupled neurons (cyberchrons) in the snail Helisoma trivolvis. This network produces regular bursts of activity which drive the motoneurons controlling the feeding musculature. Analysis of the time constants and Bode plots obtained from current injection leads to the development of an equivalent model circuit describing the functional relationships of the individual neuronal elements. The equivalent model is used to demonstrate compensation of the frequency response of an individual neuron by the effective loading of the rest of the network. However, the current observed in a postsynaptic neuron is intergrated across the long cell time constant resulting in increased temporal and spatial summation. This frequency compensation and long duration of the postsynaptic response are both believed to be instrumental in the maintenance of a high frequency burst. This model will act as a framework on which active properties such as burst form, timing, and termination can be tested.     

A Novel Planar Three-Way Power Divider

A novel planar three-way power divider is proposed. Based on the conventional planar microstrip coupled line technology, the proposed three-way power divider can modify a three-way Wilkinson power divider from a three-dimensional configuration into a two-dimensional one, meanwhile, to keep the length of the circuit to be$lambda/$4. The planar structure enables easy circuit design in printed circuit boards and monolithic microwave integrated circuits. The design concept and implementation are discussed. From the measured results, less than 4.8$pm $0.1dB of the three equivalent insertion losses, less than 19.5dB of the return loss, and better than 17.5dB of isolation at 2.4GHz can be achieved.     

一种新型宽带平面和差网络

提出了一种新型的基于环形电桥结构的宽带平面和差网络。首先提出了一种新型的宽带微带/槽线转换结构,然后将该结构引入到传统的环形电桥结构中,优化设计了一种改进型环形电桥,最后采用四个改进的环形电桥构建了双平面和差网络。测试结果表明:在4.05～7.425GHz的频率范围内,八个端口的驻波均小于2,输入端口之间的隔离度均在20dB以上,输出端口之间的隔离度大于30dB,和端口的插入损耗小于0.5dB,差端口的零值深度小于-30dB。该和差网络具有性能优良、结构简单、制作成本低等优点,在宽频带单脉冲雷达天馈系统中得到了成功的应用。     

Equivalent circuit formulation for an array of phased waveguide apertures

An expression for the radiation admittance of an infinite planar array of rectangular waveguide apertures is formulated and a technique for finding the complete equivalent circuit of the waveguide to space junction is given. The formulation includes multiple layers of dielectric above the array ground plane and waveguide elements which are center loaded with dielectric. Experimental verification of the radiation admittance formulation and the equivalent circuit concepts is given.     

高隔离度Ka波段平面魔T的设计

提出了一种适合于毫米波微波集成电路(M IC)的高隔离度平面魔T结构,该结构属于一种新型的180°平面型混合网络。基于传统的微带混合环原理,引入了微带-槽线过渡的结构,两个端口之间的180°相移通过微带-槽线转换结构实现,从而实现了输出端口的隔离。该结构采用多节阻抗匹配网络,增加了工作带宽,使微带-槽线过渡结的寄生耦合最小化。通过设计可实现得到最小尺寸的槽线终端,降低了微带-槽线过渡结的辐射损耗。引入的等效电路模型有效地提高了平面魔T的设计。借助CST软件,仿真优化了λg/4变换器以及微带-槽线转换结构的阻抗匹配,提高了隔离度。实验结果表明:在工作带宽(34～36 GHz)内,该结构输出端口2和3的隔离度达20 dB,输入端口回波损耗低于18 dB,插入损耗1 dB。     

Equivalent Circuit Modeling of a Multilayer Planar Winding Array Structure for Use in a Universal Contactless Battery Charging Platform

In this paper, an equivalent circuit model of a multilayer planar winding array structure that can be used as a universal contactless battery charging platform is presented. This model includes the mutual-inductive effects of partial overlaps of planar windings in the multilayer structure. It has been successfully simulated with PSpice and practically verified with measurements obtained from three prototypes. This circuit model forms the basis of an overall system model of the planar charging platform. It is demonstrated that model parameters can be derived from the geometry of the winding structure. Errors between the calculated and the measured results are found to be within a tolerance of 5%