Attenuation and propagation in various finline structures

The theory and numerical results of the asymmetric single and coupled bilateral and unilateral finlines and arbitrary antipodal finline considering the attenuation of the substrate are presented. Results are given to the complex propagation constant. The full wave analysis of the Transverse Transmission Line — TTL method is used in the FTD. Applying the moment method the complex propagation constant, including the attenuation constant and the phase constant, are obtained. The effective dielectric constant, ?_eff,, and the characteristic impedance are also calculated. The results are compared with the references, and news results are presented for these parameters.     

High precision analysis of finlines on semiconductor substrate

In this study, the effect of the metallization thickness in finlines on semiconcuctor substrate is researched. The propagation parameters are computed to measure the inluence of the metallization. The theory and numerical results are presented to the propagation constant and characteristic impedance of the bilateral and unilateral finlines. The full wave analysis of the transverse transmission line — TTL method is used to determine the electromagnetic fields of the structure in Fourier transform domain — FTD. Applying the suitable boundary conditions, the moment method and expanding the fields in a set of suitable bases functions, a homogeneous matrix system is obtained and the propagation constant is computed. The characteristic impedance is obtained using the relation of the voltage in the slot and the transmitted power by the structure. Computational programs are developed to obtain numerical results to the propagation parameters composed by the propagation constant and characteristic impedance.     

General analysis of electrodes in integrated-optics electroopticdevices

Integrated-optics electrooptic devices that rely on the electrooptic effect obtained by applying electric waves on the electrodes deposited on the light waveguides are considered. A general structure for the devices is presented, and a computational method for calculating the electric-field distribution in the structure is described. Comparisons between numerical and exact results are made in cases with a known solution. The effect of the thickness of the electrodes is investigated. The characteristic impedance and effective dielectric constant are presented as a function of the electrode thickness for various width-gap ratios of the electrode structure. Calculations show that the electric field in the substrate is slightly influenced by the electrode thickness, whereas the characteristic impedance and effective dielectric constant are decreased as the electrode thickness is increased     

Numerical Analysis of Shielded Coplanar Waveguides

A numerical method is presented to calculate the impedance and the effective dielectric constant for a coplanar waveguide with a ground plane under a thin dielectric. Impedance and effective dielectric constant values are given as a function of geometry for GaAs and alumina substrates. An approximate analytical expression is given to generate the numerical value of the impedance with good accuracy. The results can be used in designing shielded coplanar waveguides. Measurements of a tapered 50-Omega test structure are presented.     

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     

Theoretical and Experimental Investigation of Asymmetric Coplanar Waveguides (Short Papers)

Conformal mapping techniques are used to obtain analytic closed-form expressions for the characteristic impedance and the relative effective dielectric constant of asymmetric coplanar waveguide with infinite or finite dielectric thickness. The line asymmetry leads to a decrease of its characteristic impedance and to an increase of its relative effective dielectric constant. Six asymmetric coplanar waveguides are realized and their characteristic impedances are measured using time-domain reflectometry techniques. The experimental results show very good agreement with the theoretical ones.     

Simple and accurate formulas for a microstrip with finite strip thickness

Simple and accurate dosed form expressions for variation of characteristic impedance and effective dielectric constant of microstrip with finite strip thickness are reported. The results are in good agreement with the numerical values. These expressions are useful for microstrips used in microwave integrated circuits and computers.     

Dispersion in finlines on semiconductor and the S-parameters of a step discontinuity

The Transverse Transmission Line method is used for the characterization of bilateral and unilateral finlines on a semiconductor substrate and in conjunction with the modal method, for the calculation of the scattering parameters due to a step discontinuity on a unilateral finline with a lossless dielectric substrate. Numerical results of the effective dielectric constant, attenuation constant and characteristic impedance for the bilateral and unilateral finlines on semiconductor substrates, and results of scattering parameters of a step discontinuity for unilateral finline, are presented.     

The application of the point matching method to the analysis ofmicrostrip lines with finite metallization thickness

The characteristics of a shielded microstrip line with finite metallization thickness are calculated using the point matching method (PMM). The advantage in this case is that the method does not depend on a special geometry of the strip metallization. The approach used is based on satisfying the boundary conditions at discrete boundary points. Numerical results are presented to assert the validity of this approach in cases of large values of strip width-to-thickness ratio. It is found that an increase in the strip thickness is always associated with difficulties in convergence. The examples presented call attention to the necessity of proving the validity of the obtained solutions by other criteria. This is because good convergence behavior of the effective dielectric constant does not always guarantee the correct characteristic impedance or field distribution. In particular, the field distribution is considered as a reliable check for the numerical results     

有限尺寸介质基片上的共面波导

有限尺寸介质基片上的共面波导是一种非常接近于工程应用状态的物理模型.本文用共形映射技术分析有限尺寸介质基片上的共面波导,得到了它的单位长度电容、有效介电常数和特性阻抗等基本参数,与介质基片宽度为无限大的理想化模型作了比较,给出了介质基片为多宽可以认为是无限宽的判别公式.     

Microstrip Dispersion Including Anisotropic Substrates

A perturbation-iteration solution based on potential theory is developed for determining the effective dielectric constant, characteristic impedance, and current-charge distribution on a microstrip transmission line with isotropic and anisotropic substrates. The numerical implementation of the theory is described and is suitable for use on a personal computer. Computed data for several common substrate materials are included.     

Analysis of shielded membrane microstrip line using the finite-difference time-domain method

A simple and efficient analysis method of the shielded membrane microstrip (SMM) line using the finite-difference time-domain (FDTD) method is presented. New FDTD equations are derived using the contour path FDTD concept for the Yee cell which contains three thin dielectric sheets of membrane. The characteristic impedance and the effective dielectric constant of the SMM line are calculated using our proposed method. The method is validated by comparison with the results shown by Robertson et al. [1996].     

Quasi-static analysis of shielded microstrip transmission lineswith thick electrodes

An extended point-matching method for analyzing the shielded microstrip transmission lines with thick electrodes has been developed based on the method by Marcuse (1989). This method provides a simple and fast approach to the quasi-static analysis of the structures. The calculated fields are used to estimate the characteristic impedance and effective dielectric constant of the structures. The results agree well with available theoretical results obtained using other methods, such as the finite element method and the boundary element method. This method can be further applied to other microstrip lines widely used in monolithic microwave integrated circuits (MMICs) applications     

A broad-band U-slot rectangular patch antenna on a microwavesubstrate

A broad-band U-slot rectangular patch antenna printed on a microwave substrate is investigated. The dielectric constant of the substrate is 2.33. The antenna is fed by a coaxial probe. The characteristics of the U-slot patch antenna are analyzed by the finite-difference time-domain (FDTD) method. Experimental results for the input impedance and radiation patterns are obtained and compared with numerical results. The maximum impedance bandwidth achieved is 27%, centered around 3.1 GHz, with good pattern characteristics     

More investigations of leakage and nonleakage conductor-backedcoplanar waveguide

Through rigorous full-wave analysis, the effective dielectric constant, normalized attenuation constant, characteristic impedance, and radiation pattern of two types of conductor-backed coplanar waveguides are obtained. The analytic results show that the leakage effect is not only controlled by the thickness and dielectric constant of the substrate but also by the slot width. The leakage power transforms to a radiation space wave and a surface wave, the transverse electric field diagrams in the substrate and the far-zone radiation pattern verify the leakage phenomenon. The first structure has the maximum radiation intensity in the endfire direction, while the second one which has more leaky waves radiates into the air, is better served as a radiating device. For both structures under the nonleakage condition, the characteristic impedance is sensitive to the change of the strip width but not the slot width. Using these properties, the nonleaky and leaky circuits can exist on the same circuit board by choosing appropriate circuit dimensions     

Characteristic Impedance and Phase Velocity of a Dielectric-Supported Air Strip Transmission Line with Side Walls

The characteristic impedance and phase velocity of a dielectric-supported air strip transmission line with side walls and with center conductors having zero thickness have been obtained by means of the variational method. Green's functions are used for setting up the variational expression. Using a 22-term expansion for the charge distribution on the center conductors, the Rayleigh-Ritz method is then applied in the calculation of the characteristic impedance and phase velocity of the strip transmission line. Design curves are presented and a correction factor is derived that can be applied when the thickness of the center conductors is not zero. The design curves are quite general and apply equally well to any isotropic dielectric material that is used as a support, regardless of its dielectric constant. The experimental data presented verifies the theoretical results.     

Analysis of a TEM Cell with Septum on a Dielectric Slab

A quasi-TEM approach based on conformal transformation is used for the determination of the characteristic impedance of a rectangular coaxial line (TEM cell) having a symmetrically located inner conductor (septum) supported on a dielectric slab of equal width. The method of determination of the capacitance of the dielectric-filled portion is discussed. The results on characteristic impedance for two values of dielectric constant are presented.     

超薄微带线信号完整性的矩量法分析

超薄（或说零厚度）微带线是微波电路设计的重要组成部分。基于矩量法,推导了零厚度微带线电磁参量的公式,计算了微带线的特性阻抗和相应的等效介电常数,探讨了微带线的准静电边缘效应和两条微带线间的近端串扰问题。计算结果与已有结果相比较,一致性良好。     

Investigation of a frequency-selective surface based on a planar mushroom-shaped metamaterial with an electronically tunable stopband

A design of a band-stop frequency-selective surface based on a planar mushroom-shaped metamaterial with an electronically tunable stopband has been proposed and investigated. The results of numerical simulation and experimental measurements of the parameters of a finite section of the metamaterial with mounted varicaps are presented. These results illustrate the shift of the structure stopband occurring simultaneously with a change in the capacitance of the lumped elements. Frequency dependences of the inherent dielectric parameters have been obtained. They indicate the presence of negative values of the effective permittivity and effective permeability of the proposed structure and the presence of the surface impedance that significantly exceeds the free-space characteristic impedance and is frequency-tunable.