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.     

Accurate closed-form formulas for the electromagnetic parameters of squared coaxial lines

This article presents a set of accurate closed-form formulas for the electromagnetic parameters (inductance (L), capacitance (C) and characteristic impedance (Z_c)) for squared coaxial lines with circular and square inner conductor. The analytical expressions, deduced from rigorous analysis by the finite element method (FEM), method of moments (MoM) and curves fitting techniques, can be easily implemented in CAD simulation tools, to design components for wireless communication. This study presents accurate and suitable general expressions for all squared coaxial lines with a wide range of outer to inner conductors ratio between 1.2 and 10. As an application, we present the design of 60 GHz branch line couplers.     

Features of the coupling coefficients of planar stepped-impedance resonators at higher resonance frequencies and application of such resonators for suppression of spurious passbands

Features of the electromagnetic coupling coefficients between stepped-impedance resonators made of the sections of symmetric strip and microstrip transmission lines at higher resonance frequencies are investigated. It is found that, in stripline resonators, these coefficients are equal to zero at some coordinates of the jump of the characteristic impedance. A new method of expansion of the stopband of bandpass filters, which is based on suppression of the first spurious bandpass and frequency diversity of the main band and the second spurious bandpass is proposed. A Chebyshev bandpass filter with a center frequency of 2.45 Hz and a spurious band at 6.06 f ₀ is manufactured and tested to demonstrate the proposed method.     

正多边形外导体-圆形内导体同轴传输线特性阻抗的计算

本文提出一种计算正多边形外导体-圆形内导体同轴传输线特性阻抗的方法。由它可以得到正三(四、五、六)边形外导体-圆形内导体同轴传输线特性阻抗的可靠的上限和下限值。当r/R0.5(0.6)时,由它得到的上限和下限值十分接近,有一定的实用价值。     

Improving the Gain-Frequency Performance of Cascaded Single-Stage Distributed Amplifiers with Bandpass Filter Structure

In this paper a bandpass filter structure is proposed for realizing the artificial transmission lines of cascaded single-stage distributed amplifiers (CSSDA) and the basic analysis and design of the bandpass structured CSSDA (BP-CSSDA) is demonstrated. Some of the lower frequency region in the gain-frequency band of the CSSDA is not utilized due to presence of the bias components in traditional design methods. By using the bandpass structure for the realization of artificial transmission lines, the unused portion of the gain-frequency band can be utilized. Therefore, one can obtain more bandwidth using the bandpass type artificial lines in the CSSDA than using the lowpass type lines. The gain of a CSSDA can be increased, by increasing the interstage termination impedance (Z _0int) without compromising the bandwidth. In this paper, a graphical method for determining the optimum Z _0int is introduced. Simulation results showing the advantage of using the BP structured artificial lines in the CSSDA is provided.     

复杂截面同轴线特性阻抗、截止波长的计算

应用静电场的观点和导波传输理论,用有限元法（FEM）分别计算了各种复杂截面同轴线特性阻抗、截止波长。计算结果表明,该方法计算精度高,通用性强,简便易行,可以用于传输线工程问题的设计和计算。     

Design of new quadruplexer with compact size,high isolation and wide stopband

This study presents a quadruplexer (1.8/2.4/3.5/5.8 GHz) with compact size, high isolation, low insertion loss and wide stopband based on the multi-mode resonators. The quadruplexer is composed of four pairs of coupled multi-mode resonators (uniform impedance resonator, UIR and stepped impedance resonators, SIRs) and the source–load coupling lines. Each channel (passband) can be easily determined by tuning the impedance ratio (K) and length ratio (α) of the SIRs so as to implement a 2-order bandpass filter individually. The source–load coupling lines are designed to correspond to the quarter-wavelength of the center frequency at each channel. The proposed quadruplexer shows a simple configuration, an effective design method and a small circuit size.     

基于DisplayPort标准的铜缆数据连接线特性阻抗分析

文章分析了铜缆传输双绞线的特性阻抗的理论计算方法,为研发与实现基于Displayport1.1标准的铜缆传输线提供了工程依据。文章以具体的工程实例,说明对于高频传输线的生产与制造过程中怎样保持其特性阻抗的一致性,进而为提高高频传输线阻抗特性指出了较清晰的控制方法。对于高频线缆的生产具有较高的参考价值。     

The Compensation of Step Discontinuities in TEM-Mode Transmission Lines

A method for the compensation of the effects due to discontinuities that arise when transmission lines of different characteristic impedance are joined is presented. The proposed method is not based calculating the equivalent circuit of the discontinuity but makes use of simple taper on the wider line at an impedance step to remove the effects of the discontinuity.     

结合保角变换的优化模拟镜象法解多种截面形状同轴线的特性阻抗

介绍一种计算多种截面形状同轴线的新方法结合保角变换的优化模拟镜象法。此法计算量小、精确度高,并能进行误差范围计算。列出对内圆外方、偏心内圆外方和内带形外圆等九种同轴线特性阻抗的计算结果并与其它文献结果进行了比较。     

Sur les méthodes de calcul de l’exposant linéique de propagation et d’impédance caractéristique des câbles aériens et enterrés

The propagation constant of a line or a cable, and its characteristic impedance represent two parameters which are needed in order to calculate the variation as a function of the time of a current induced by an emp.For the aerial lines expressions which take into account the presence of the soil could be developed but the case of the buried conductors is of a more difficult approach. The aim of this study is to present solutions introduced by different authors and to compare them with a calculation method for the propagation constant using iterations, proposed by the authors. If this value is known it is shown that the characteristic impedance calculation of buried cables can be improved by avoiding the necessity to compute with a reasonable precision the impedance of the ground.     

Development of a standard for transient measurement of junction-to-case thermal resistance

The paper summarizes the development of a standard method to measure the thermal resistance “junction-to-case” θ_JC of semiconductor devices with heat flow through a single path. Power switches or amplifiers are typical examples. θ_JC is a key performance metric to decide whether a device can be used in thermally critical applications. Hence an accurate and reproducible method to measure θ_JC is required. This is not easy, especially for low θ_JC, which is reflected by the fact that no JEDEC industry standard existed then to measure θ_JC. During the last 4 years we have evaluated approaches and developed a new method called Transient Dual Interface (TDI) method. It uses two measurements of the thermal impedance Zth or more specific Z_θJC(t) of the device with different cooling conditions at the interface of device case and a heat sink. To evaluate these measurements two methods are applied. Method 1 determines θ_JC directly from the separation of Zth-curves. θ_JC is the thermal impedance Z_θJC(t_s) at the time t_s where the two Z_θJC(t)-curves separate. Method 2 first calculates cumulative structure functions and uses their separation point to determine θ_JC. Both data evaluation methods complement each other, because method 1 is most accurate for low θ_JC in the range of 1 K/W or below, while method 2 is more accurate for higher θ_JC > 1 K/W. The TDI method allows to measure θ_JC with higher accuracy and better reproducibility than the steady state method used in industrial practice up to now. The TDI method was published as JEDEC standard JESD51-14 in November 2010. Problems of the traditional steady state measurement and main steps of the development of the TDI method are discussed.     

Generalization of the Fast Hough Transform for Three-Dimensional Images

This study is devoted to the analysis of algorithms of calculating the fast Hough transform for two- and three-dimensional images. A method for calculating the fast Hough transform (FHT) for straight lines in a three-dimensional image is proposed; its space and time complexity are Θ(n⁴), where n is the characteristic linear size of the input image. The FHT algorithms for approximation in two- and three-dimensional spaces are considered, and properties of the accuracy and completeness of the corresponding sets of dyadic patterns are investigated.     

Rigorous Analysis of the Disk-Loaded Waveguide Slow-Wave Structures

Recently disk-loaded waveguide has been widely used in high-power traveling wave tubes (HPTWT). Although TM ₀₁ mode is it's main mode, the asymmetry mode may be excited by slight asymmetry of the structure, misalignment of the beam, or the asymmetry associated with the input or output structure. So research about asymmetry mode of disk-loaded waveguide is necessary. The general dispersion equation and interaction impedance expression of disk-loaded waveguide is obtained with accurate field theory for the first time. Based on these results, a broadband and a narrowband disk-loaded waveguides are designed which can be used in the Ka band HPTWT. Moreover, the theoretical calculated results are compared with the simulated results from the HFSS (High Frequency Structure Simulator) code using finite element method. It is found that frequency domain overlapped by these two modes of the narrowband structure is very narrow, so the HEM ₁₁ mode may be ignored when calculating Beam-wave interaction. In the other hand, the interaction impedance of HEM ₁₁ mode is very low generally.     

Variation in optical-absorption edge in SiN<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> layers with silicon clusters

Using optical methods, data on optical constants are obtained for silicon nitride films synthesized by plasma-chemical vapor deposition (PCVD). Models for calculating the permittivity in the model of inhomogeneous phase mixture of silicon and silicon nitride are considered. It is found that the optical-absorption edge (E _g) and the photoluminescence peak shift to longer wavelengths with increasing nitrogen atomic fraction x in sin _x films. When x approaches the value 4/3 characteristic for stoichiometric silicon nitride Si₃N₄, a nonlinear sharp increase in E _g is observed. Using Raman scattering, Si-Si bonds are revealed, which confirms the direct formation of silicon clusters during the film deposition. The relation between the composition of nonstoichiometric silicon nitride films, values of permittivity, and the optical-band width is established for light transmission.     

Analysis of Millimeter Wave Scattering by the Infinite Plane Metallic Grating Using PCG-FFT Technique

In this paper, both fast Fourier transformation (FFT) and preconditioned CG technique are introduced into method of lines (MOL) to further enhance the computational efficiency of this semi-analytic method. Electromagnetic wave scattering by an infinite plane metallic grating is used as the examples to describe its implementation. For arbitrary incident wave, Helmholz equation and boundary condition are first transformed into new ones so that the impedance matrix elements are calculated by FFT technique. As a result, this Topelitz impedance matrix only requires O(N) memory storage for the conjugate gradient FFT method to solve the current distribution with the computational complexity O(N log N) . Our numerical results show that circulate matrix preconditioner can speed up CG-FFT method to converge in much smaller CPU time than the banded matrix preconditioner.     

Constant Impedance TEM Horn Antenna: Aperture and Characteristic Impedance’s Impacts on Axial Electric Field

TEM horn antenna with constant characteristic impedance (CCI TEM horn antenna) is a widely used ultra-wideband (UWB) antenna. Considering the peak-to-peak value of the axial electric field (V_pp), how to design such antenna’s characteristic impedance (Z _c) has not been involved in previous research. The relationship between V_pp and antenna aperture as well as characteristic impedance is numerical analyzed. The simulation and experimental results show that the optimal aperture is existed to maximize V_pp when the antenna’s length is fixed at the axis. More over, V_pp of the antenna with optimal aperture reaches the maximum value when the characteristic impedance is 280 ohm.     

Analytical analyses of v, elliptic, and circular-shaped microshieldtransmission lines

Several new types of monolithic coplanar transmission lines, v, elliptic, and circular-shaped microshield coplanar waveguide, have been proposed. The characteristic impedance expressions for those transmission lines have been derived using the conformal mapping method (CMM) under the assumption of the pure-TEM propagation and zero dispersion. In the analyses of the elliptic and the circular-shaped microshield coplanar lines, the methods using the graphical approximation and taking the geometric mean value of the upper and the lower bounds to the size of the line are put forward to calculate the characteristic impedance of this two kinds of microshield coplanar lines. The numerical results show the effects of the different shaped microshield walls on characteristic impedances     

AC conductivity of nanoparticles CoxFe(1−x)Fe2O4 (x=0, 0.25 and 1) ferrites

Nanoparticles of Co_xFe_(1−x)Fe₂O₄ (x=0, 0.25 and 1) were prepared by the chemical co-precipitation method. X-ray diffraction and scanning electron microscopy were used to determine the average particle size and morphology of the prepared samples. AC conductivity is found to vary as ω^s in the frequency range 42–5×10⁶ Hz. The impedance analysis reveals that low conductivity and high impedance values are observed at low temperatures. The Nyquist impedance plots of the present investigation clearly depict the inherent phenomenon involved in the conduction mechanism of Co doped Fe₃O₄ ferrites. Regarding frequency dependence of Co_xFe_(1−x)Fe₂O₄ AC conductivity the observed behavior clearly indicates that the present ferrites are semiconductor-like.     

计算多层印刷传输线色散特性的一种简单方法

本文给出计算多层印刷传输线色散特性的一种简单方法，本方法利用ＴＥ波及ＴＭ波的平面结构谱域等效电路，导出二维谱域并矢格林函数，再利用格林函数由积分方程的解给出传输常数，进而求得特性阻抗表示式。用本文方法所得到的数值结果和更复杂的方法所得到的结果非常一致。