一种分析有限金属厚度和有限电导率的共面波导结构的有效方法

采用分区直线法与渐近拟合阻抗边界条件相结合的方法,对一种具有限金属厚度和有限电导率的共面波导结构的相对介电常数和损耗特性进行了分析,这是一种全波分析方法,并且可以适用于趋肤深度与金属厚度之比为任意数值的情况。计算实例证明了该方法的正确性和有效性。     

Effect of substrate thickness and metallization thickness on dispersion characteristics of CPW

Approximate conformal mapping techniques have been used for analysing the effect of finite substrate thickness on coplanar wave guide (CPW). Calculations for impedance and effective dielectric constant are presented for CPW's with finite substrate thicknesses. Analytical formulation are presented for calculations. Network analytical methods of electromagnetic fields are employed to evaluate the effect of thick metal coating on CPW. Dispersion characteristics of CPW have been plotted for various metallization thicknesses. Effect of thick metal coating on guide wavelength is also plotted. Increase in metallization thickness of CPW causes an increase in wavelength. Due to this fact characteristic impedance and effective dielectric constant decreases.     

Full-wave analysis of coplanar waveguide discontinuities using thefrequency domain TLM method

This paper presents a full-wave analysis of a variety of coplanar waveguide discontinuities using the frequency domain TLM method. The finite metallization thickness is taken into account as well as metal losses and the interaction of fundamental and higher order modes between cascaded discontinuities. Numerical results are presented for the frequency-dependent s-parameters of transitions between CPW and slotline, CPW and microstrip line and CPW-microstrip overlap transition. The effect of interactions between the CPW discontinuities and the CPW airbridges is also investigated     

A 3-D mode matching technique for the efficient analysis ofcoplanar MMIC discontinuities with finite metallization thickness

A technique is proposed for the efficient analysis of CPW discontinuities including finite metallization thickness. The transverse resonance technique (TRT) is modified by introducing an impressed source that allows a cavity of fixed, instead of variable, dimensions to be analyzed (impressed source technique, IST). At the same time, as with TRT, the field analysis of only homogeneously filled waveguides is required so avoiding the computation of frequency dependent as well as complex modes as with the conventional mode matching technique. On this basis, an extremely efficient code for the analysis of CPW discontinuities, applicable also to interacting discontinuities, is obtained. The same code, which incorporates the modal spectrum of an L-shaped waveguide, can be used to compute a large class of CPW discontinuities including steps, gaps, open ends, etc. Computed results are shown to be in remarkable agreement with the experiments and confirm that the finite metallization thickness may significantly affect the electrical characteristics of CPW circuits     

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     

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     

共面波导有限金属厚度效应的研究

用保角变换法对共面波导金属厚度效应进行了理论分析，编制了相应的计算机程序，给出了数值解，并对此进行了多元曲线拟合，导出了考虑金属厚度后的形状比k、有效介电常数、特征阻抗、损耗的闭定表达式。用此修正表达式求得特征阻抗及损耗的数值解，并与K．C．格普塔的修正值及实验测量值进行了详细比较，结果表明此修正公式与实验值相符较好。     

The influence of finite conductor thickness and conductivity onfundamental and higher-order modes in miniature hybrid MIC's (MHMIC's)and MMIC's

The effect of finite metallization thickness and finite conductivity on the propagation characteristics of conductor-backed CPW on thin substrate is rigorously analyzed. A self-consistent approach is used together with the method of lines (MoL) to determine the propagation constant, losses and field distribution of the fundamental and first two higher-order modes in coplanar waveguides (CPWs) with finite metallization thickness and lossy backmetallization. The method used is general and can be applied to miniature MHMICs and MMICs including lossy semiconductor substrate. It is shown that the onset of higher-order modes limits the usable frequency range of conductor-backed CPWs. The analysis also includes microstrip transmission lines on thin substrate material. It is demonstrated that a resistive strip embedded into the microstrip ground plane may potentially be useful in the design of integrated planar attenuators     

Analysis of Finline with Finite Metallization Thickness (Short Papers)

In this paper, we present a method for analyzing finline structures with finite metallization thickness. The method is based on a hybrid mode formulation but it by-passes the lengthy process of formulating the determinantal equation for the unknown propagation constant. Some numerical results are presented to show the effect of the metallization thickness for unilateral and bilateral finlines.     

Analysis of the Characteristics of an Earthed Fin Line

This paper presents a theoretical and experimental investigation of the effective permittivity and the characteristic impedance of the earthed unilateral fin line. Using the Ritz-Galerkin method, the eigenvalue equation for a fin line with finite metallization thickness as well as a longitudinal slit in the metal waveguide mount is derived. The numerical solution converges very rapidly in all the cases investigated. Experimental checks are reported, which verify the results of this method and stress the importance of the effects of the finite metallization thickness and longitudinal slit in the mount at higher frequencies. The theoretical results are compared with results by Hofmann, and they are found to correspond closely.     

Investigations of complex modes in a generalized bilateral finlinewith mounting grooves and finite conductor thickness

A generalized bilateral finline with mounting grooves and finite conductor thickness is analyzed by a full-wave mode-matching method. The final nonstandard eigenvalue equation is derived from the unknown coefficients in the slot regions to reduce the size of the matrix equation. The convergence studies of the mode-matching method is first studied for the fundamental mode of a symmetric bilateral finline. Both the propagation constant and the characteristic impedance as defined by the power-voltage relationship are analyzed and compared to the existing data. Excellent agreement is obtained. The effects of metallization thickness and mounting grooves are discussed. The accurate results obtained for the fundamental mode by the mode-matching method with respect to both relative and absolute convergence were also obtained for the complex modes of the finline. The dispersion characteristics of the fundamental, higher order, evanescent, and complex modes are presented for an asymmetric bilateral finline. The effects of mounting grooves and metallization thickness on the complex mode propagation constants are investigated and discussed     

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     

Analysis of a shielded microstrip line with finite metallizationthickness by the boundary element method

A boundary element method is presented for the quasi-static analysis of a shielded microstrip line with finite metallization thickness. The analysis is based on the solution of a system of boundary integral equations which are derived from Green's second identity. Numerical results for the charge distribution along the strip and the effects of metallization thickness on line characteristics are presented. The results show good agreement with data available in the literature     

Attenuation Characteristics and Sensitivity Analysis for Coplanar Waveguide

The behaviour of attenuation losses in Coplanar waveguides (CPW) is studied for quasi-planar transmission lines with constant characteristic impedance (Z₀) and resistivity, having different geometry's. This behavior helps in making a suitable choice of the type of structure and its dimensional parameters depending upon the application. Minimization of loss for a chosen substrate thickness, conductivity and impedance is analyzed. Dispersion characteristics of CPW have been plotted for various metallization thicknesses. A sensitivity analysis for effective dielectric constant with respect to various dimensional parameters of CPW is presented.     

Full wave analysis of conductor-backed and multi-layer high-T c superconducting coplanar waveguide

Dispersions, attenuation and characteristic impedance of shielded conductor-backed coplanar waveguide(CBCPW) and shielded three-layer coplanar waveguide (CPW) with finite conductor thickness as well as their superconducting applications are calculated. The method of lines(MoL) is employed to analyze these coplanar waveguides. The analysis is validated by a comparison of the calculated results with those published previously. Effects of finite width of grounded strip for a CPW are considered. Extensive investigation of the numerical convergence for calculation of the characteristic impedance is also described.     

A CPW T-resonator technique for electrical characterization ofmicrowave substrates

An impedance independent method is proposed using a finite ground coplanar waveguide (CPW) T-resonator to electrically characterize microwave materials. Silicon-based CPW T-resonators are designed and measured, with calibrated data agreeing well with other methods up to 30 GHz. Uncalibrated measurements produce dielectric constant and attenuation results within 3.7% and 25%, respectively, of those obtained with calibration. Hence, the CPW T-resonator can be used to provide rapid and accurate characterization of microwave substrates with unknown dielectric properties     

Low-loss CPW on low-resistivity Si substrates with a micromachinedpolyimide interface layer for RFIC interconnects

The measured and calculated propagation constant of coplanar waveguide (CPW) on low-resistivity silicon (1 Ω·cm) with a micromachined polyimide interface layer is presented in this paper. With this new structure, the attenuation (decibels per centimeter) of narrow CPW lines on low-resistivity silicon is comparable to the attenuation of narrow CPW lines on high-resistivity silicon. To achieve these results, a 20-μm-thick polyimide interface layer is used between the CPW and the Si substrate with the polyimide etched from the CPW slots. Only a single thin-film metal layer is used in this paper, but the technology supports multiple thick metal layers that will further lower the attenuation. These new micromachined CPW lines have a measured effective permittivity of 1.3. Design rules are presented from measured characteristics and finite-element method analysis to estimate the required polyimide thickness for a given CPW geometry     

Full-wave boundary integral equation method for suspended planartransmission lines with pedestals and finite metallizationthickness

A boundary integral equation method is proposed for the full-wave analysis of suspended planar transmission lines with pedestals and/or finite metallization thickness. Coupled boundary integral equations are formulated on equivalent magnetic currents only on the apertures of subregions using the Green's identity of the second kind. Because it is possible to take a large number of terms in the series expansion of Green's functions in each subregion independently from the order of resulting matrices, this approach can avoid the relative convergence problem. Numerical results for suspended coplanar waveguides are found to have a stable convergence property and to be in excellent agreement with other available theoretical results. Numerical data reveal the effects of conductor thickness and aperture width on the transmission properties of suspended planar transmission lines with pedestals     

Efficient electromagnetic analysis of line-fed aperture antennas in thick conducting screens

This paper presents a numerical and experimental verification of an approximate but efficient integral equation technique for the scattering by apertures in conducting planes with finite thicknesses. The approach is based on a perturbation method and modified Green's functions that take into account the finite metallization thickness. The computational effort and time needed for solving the problem are the same as in zero-thickness case. When compared to full-wave cavity treatment of thick apertures, the method is (depending on the number of unknowns) at least an order of magnitude faster. The method can be applied even to apertures of arbitrary shapes where computing the cavity's Green's functions is a difficult task. The results of simulations using the new approach show good agreement when compared to both results from full-wave cavity approach and measurements.     

Explicit formulas of propagation characteristics for unilateral finline

In this paper, the unilateral fintine characteristics including finite metallization thickness and depth of mounting grooves are analysed by transverse resonance principle combining moment method. The numerical results are presented, the influence of the finite metallization thickness and depth of grooves on the propagation characteristics are investigated in detail. Finally, a set of explicit formulas for the propagation characteristics of unilateral fintine are developed. To be compared with the rigorous numerical results, the errors are within ±1% for phase constant and ±2% for characteristic impedance respectivelly.