Characterization of shielded coplanar type transmission linejunction discontinuities incorporating the finite metallizationthickness effect

Frequency-dependent characteristics of shielded junction discontinuities between coplanar type transmission lines, specifically coplanar waveguide (CPW) and finline, are analyzed by the mode-matching technique. The effect of finite metallization thickness is also incorporated in the analysis for the first time. Scattering parameters of finline step discontinuity are compared with existing data to confirm the accuracy of the approach. Numerical results for finline step discontinuity, shielded CPW step discontinuity and CPW-finline transition are presented     

Efficient full-wave analysis of stratified planar structures andunbiased TW-FET's

We have developed a rigorous full-wave analysis technique capable of characterizing quasiplanar travelling wave structures, consisting of multilayer dielectrics and conductors of finite thickness, also taking into account dielectric and conductor losses. We have studied boxed embedded microstrips and another complex passive structure, namely the T-gate TW-FET, devoting particular attention to the distribution of current inside the metallization. All structures considered were simulated by means of a desktop computer. We have tested our program by comparing our results with experimental data of embedded microstrips and employed it for the characterization of planar and T-type gates of the FET's without bias     

Narrow-band microstrip bandpass filters with low radiation lossesfor millimeter-wave applications

Microstrip lines are attractive for the lower millimeter-wave ranges, but use of relatively thick substrates would be desirable in order to minimize losses. On such substrates the usual types of microstrip narrowband bandpass filters (formed from, e.g. coupled line segments with open ends) tend to radiate strongly giving very poor performance. It has been found that a grating technique initially developed for use with dielectric waveguides can be adapted for microstrips to obtain narrowband millimeter-wave microstrip filters with little radiation and strong filter characteristics. The stopbands are broad, the second passband occurring at three times the frequency of the first passband. These filters use parallel-coupled gratings with a single grating in cascade at each end. The modifications to the dielectric waveguide filter theory that are necessary for use with microstrips are detailed. Experimental results from microstrip realizations, which demonstrate their potential for millimeter-wave microstrip applications, are also presented     

A Modified Mode-Matching Technique and its Application to a Class of Quasi-Planar Transmission Lines

A rigorous and versatile hybrid-mode analysis is presented to determine the normalized propagation constants in a class of quasi-planar transmission-line structures. The method is accurate and covers the finite metallization thickness, mounting grooves, and an arbitrary number of dielectric subregions. Utilizing a modified mode-matching technique, one can derive discontinuity and transmission-line matrices for each homogeneous subregion. Successively multiplying matrix equations of all subregions leads to the characteristic matrix system. This procedure makes it possible to create a modularized computer program which can be conveniently extended to a wide spectrum of conceivable configurations simply by inserting the matrix equations of additional subregions in the multiplication process. To demonstrate the efficiency of the proposed method, dispersion characteristics of dominant and next higher order hybrid modes in earthed and insulated finlines, suspended microstrips, and coupled striplines with tuning septa, are given as examples.     

A Dispersion Model for Coupled Microstrips

The frequency-dependent propagation characteristics of symmetrical, nonsymmetrical, and multiple coupled microstrips are evaluated by utilizing a directly coupled parallel-plate ideal waveguide model. The closed-form expressions for the frequency-dependent parameters of this proposed semi-empirical utility model are derived in terms of the quasi-static parameters of the coupled microstrip structure. These model parameters are then used to evaluate the frequency-dependent propagation characteristics, including the normal-mode effective dielectric constants and impedances of the coupled microstrips. These results are found to be in good agreement with all the published experimental results and the numerically computed values for symmetrical and nonsymmetrical coupled microstrips. The model should be useful in the computer-aided design of coupled microstrip structures at higher frequencies where the dispersion effects become important.     

衬底材料对微带线间串扰耦合的影响研究

随着系统频率的提高,衬底材料特性已成为影响信号走线之间串扰的一个不可忽略的因素。该文基于传输线方程和频域S参数对两平行微带线间串扰耦合进行理论分析,并结合全波3维电磁场仿真工具对具有不同介电常数和不同厚度的衬底材料进行了仿真和分析,得到了微带线在不同衬底下的电场分布,以及近端和远端串扰随频率、衬底介电常数和厚度变化的曲线。随着频率的增大,远端串扰将大于近端串扰,并且随着衬底介电常数和厚度的增加,微带线间的串扰呈现正弦上升的变化趋势。     

Printed Circuit Transmission-Line Characteristic Impedance by Transverse Modal Analysis

Dispersion characteristics of printed circuit transmission lines such as finlines, shielded microstrips, slotlines, suspended striplines, coupled slotlines, and coupled striplines computed by the transverse modal analysis were reported in a previous paper. Application of the transverse modal analysis to compute the characteristic impedances of these printed circuit transmission lines is illustrated in this paper. Favorable comparison with various published data demonstrates the outstanding accuracy achieved by this technique. Combining the characteristic impedance computation with the dispersion results, the transverse modal analysis can be employed for solving various problems in printed circuit transmission lines.     

Quasi-static analysis of shielded planar transmission lines withfinite metallization thickness by a mixed spectral-space domain method

A new method to analyze shielded planar transmission lines with finite metallization thickness is described. It is based on a mixed spectral-space domain representation of the Green's function. The method allows the accurate determination of the static parameters of the transmission line with great efficiency as compared to methods available in the literature. Several numerical examples are shown on single and coupled planar transmission lines     

Computation of frequency-dependent propagation characteristics ofmicrostriplike propagation structures with discontinuous layers

A general procedure based on the method of lines is presented for the full-wave analysis of propagation structures having layered substrates with step inhomogeneities in each layer. Examples of such structures include microslab lines and microstrip near a substrate edge. It is shown that with this extended method of lines technique the frequency-dependent characteristics, including the modal impedance, current distribution, and other properties of these structures, can be calculated. To illustrate the technique, typical structures such as microstrips on a finite-width dielectric slab and microstrips near a substrate edge are considered, and the effect of the proximity of the edge on the propagation characteristics of the microstrip is computed. For the case of a microstrip near a substrate edge, the numerical results obtained are compared with measured values of propagation constants, showing that the proximity effect is predicted to within 1%     

Hybrid-mode computation of propagation and attenuationcharacteristics of parallel coupled microstrips with finitemetallization thickness

The hybrid-mode mixed spectral domain approach (MSDA) is formulated to investigate the dispersion nature of multiple coupled microstrip lines with arbitrary metallization thickness. Incorporated into the solution procedure, a new set of basis functions with δ ^-1/3 field singularity near conductor edges is found to be effective in calculating both the phase and attenuation constants. The computation of conductor loss is based on the perturbation procedure. Over a broad band of frequency spectrum, excellent agreement is obtained between the calculated results and existing experiment data for the metallic losses of a single microstrip and effective dielectric constants of coupled lines. The influence of finite metallization thickness on the frequency dependent modal propagation and attenuation characteristics is presented for both a three-line and four-line structure     

The influence of metallization thickness on the characteristics ofcascaded junction discontinuities of shielded coplanar type transmissionline

A full-wave analysis based on the mode-matching technique is applied to analyze cascaded junction discontinuities of coplanar-type transmission lines, coplanar waveguide (CPW) and finline. Results for a CPW-finline transition, a shielded CPW gap and a symmetric notch incorporating the finite metallization thickness effect are presented. The influence of metallization thickness on the coupling effect exhibited by cascaded junction discontinuities is also presented and discussed     

Propagation characteristics of coplanar-type transmission lineswith lossy media

Lossy coplanar-type transmission lines are analyzed based on the hybrid-mode formulation by combining the spectral-domain approach with the perturbation method. Introducing a finite thickness of metallization and choosing the proper basis functions for the thick conductor model prevent the integrals used for calculating the conductor losses from becoming singular when evaluated at the conductor edge. An orthogonality relation is used to reduce the double infinite or semi-infinite integral to a single integral, thus reducing the computation effort drastically. Numerical computations by new basis functions for the thick conductor show convergence rates as fast as those for the zero-thickness cases. Numerical results include the effective dielectric constants, characteristic impedances, and total losses (conductor and dielectric losses) for slot lines and symmetrical and asymmetrical coplanar waveguides     

Metallization thickness effect of striplines with anisotropicmedia: quasi-static and hybrid-mode analysis

The effect of metallization thickness in striplines is investigated on the basis of the quasi-static and frequency-dependent hybrid-mode formulations. The formalism utilizes the aperture fields as source quantities and uses the extended version of the network analytical methods of electromagnetic fields. It is therefore applicable for the general structure, i.e., coupled thick strips with uniaxially anisotropic media. Numerical computations include comparisons with available data for the simpler cases to show the accuracy of the present method and the quasi-static and frequency-dependent hybrid-mode solution for single and coupled thick strips with anisotropic media     

Insertion loss of magnetostatic-surface wave transducers $transmission-line model and experiment

In this paper, a transmission-line model is developed for the computation of the insertion loss of magnetostatic-surface wave transducers and measurements are carried out by the authors to check this model. In a first step of the analysis, closed-form expressions for the solution of the telegrapher's equations for the two microstrip transducers are obtained. The insertion loss is then derived from this solution as a function of three transmission-line parameters, i.e., the propagation constant and the characteristic impedance of the YIG-loaded microstrip line and the mutual inductance between the two microstrips, these quantities being, in general, complex. In a second step, these transmission-line parameters are numerically computed by applying a full-wave method-of-moments technique. Thus, the theoretical results obtained are found to be in good agreement with experimental results.     

Hybrid Mode Analysis of Microstrip Lines on Anisotropic Substrates

A rigorous hybrid mode analysis is applied to microstrip lines on anisotropic substrates to determine its high-frequency performance. The analysis is based on a general formulation of the problem of planar transmission lines on multilayered substrates with uniaxial anisotropy, of which the microstrip line is a special case. Exact solution is obtained using a functional equation technique which was previously developed and applied to microstrip and bilateral finlines. The results were used to check the validity of the concept of equivalent isotropic substrate, suggested by some authors to simplify the calculation of the parameters of these lines. Certain approximations are introduced to allow the efficient calculation of the characteristics of microstrips on anisotropic substrates at relatively high frequencies or for wide strips. Numerical results are given for some values of the parameters of microstrip lines on sapphire and include the regions of excitation of higher modes.     

Full-wave analysis of coplanar strips considering the finite stripmetallization thickness

An extensive analysis, based on a full-wave mode-matching technique, is described for coplanar strips (CPS) incorporating the strips' finite metallization thickness. Results for the effective dielectric constant and characteristic impedance are presented to show the effect of the metallization thickness. It is found that the characteristic impedance has a strong dependence on the metallization thickness, which signifies the fact that the finite metallization thickness needs to be considered in designing practical microwave circuits employing CPS. Numerical results of CPS with zero metallization thickness obtained using this method are found to be in good agreement with those published previously. Extensive investigation of the numerical convergence of these results is also described     

The effects of a dielectric capacitor layer and metallization onthe propagation parameters of coplanar waveguide for MMIC

The study of coupling phenomena between lines laid on semiconductor substrates in monolithic microwave integrated circuit (MMIC) technologies and the determination of propagation effects on power FETs require the characterization of lines with micron transversal widths. For such lines, the influence of metallization thickness and dielectric cap layer on propagation properties can not be neglected. These effects are characterized for the case of coplanar lines laid on semiconductor substrates. The mathematical development used and the results obtained by a numerical technique are presented     

降低有损耦合微带线间串扰的方法分析

为降低和控制有损耦合微带线间的串扰,在强信号线两边各插入了一列用金属填充的、顶端用微带连接的接地孔.利用FDTD方法对该结构进行模拟并利用FEM法进行了验证.模拟结果表明串扰衰减程度与基底介质的损耗、接地孔参数有关.     

Design of an Overlay Directional Coupler by a Full-Wave Analysis

A full-wave analysis based on the spectral-domain method is applied to coupled overlay microstrips, coupled inverted microstrips, and coupled microstrips. Exclusive numerical data including frequency characteristics are included. A 10-dB overlay coupler was built according to the design theory, and experimental results are reported.