Application notes - basic parameters of coplanar-strip waveguides on multilayer dielectric/semiconductor substrates, Part 1: high permittivity superstrates

A simple method and closed-form analytic formulas for symmetric CPS based on single layer substrate (infinite and finite thickness) and multilayer lossy dielectric (semiconductor) substrate, where the permittivity of the superstrate layers decrease away from the strips, are proposed. Since the line models are given analytically, the dependencies of the line parameters may be analyzed and optimized in wide ranges of sizes, permittivities, and losses (substrate resistivity). In general, the formulas are reversible. The measured line parameters may be used to calculate the permittivity and loss tangent (resistivity) of one of the substrate layers if the parameters of the other layers and strips are known. The method may be easily extended to include larger number of substrate layers.     

Permittivity measurement of disk and annular dielectric samples using coaxial transmission line fixtures. part II: experimentation and accuracy analyses

An improved permittivity measurement technique for dielectric disks involving S-parameter measurement of a two-port coaxial transmission line fixture is presented. The previous form of the method suffers from variation of the retrieved permittivity with frequency, which leads to inaccuracies that may be severe at some frequencies. An extension of the method that reduces these errors is devised. In addition, an independently developed new technique for measuring the permittivity of annular samples via quadratic curve fitting is presented. This technique also involves S-parameter measurement of a coaxial fixture and requires measurement of only three known materials (one of them may be free space, in which case the requirement is reduced to only two solid dielectrics). The permittivity of any unknown dielectric may subsequently be determined with high accuracy over a wide frequency range. The method is based on the premise that the variation of the reflection characteristics of the two-port coaxial transmission line fixture with the permittivity of the sample displays a strongly quadratic behaviour. This paper constitutes the second of two parts of this work. Part I, also appearing in this issue, presents the theoretical formulation for the moment method mode-matching treatment of the coaxial fixture for treating annular samples. In the present paper, the measurement techniques are described, and numerical simulations of the experimental procedure based on the theory of Part I are presented. In addition, comparative results of accuracy for these two approaches are given. Sensitivity analyses are also presented, along with preliminary experimental results.     

Permittivity measurement of disk and annular dielectric samples using coaxial transmission line fixtures. part I: theory and formulation

One way of measuring the permittivity of circularly shaped dielectric samples is to measure the S-parameters of a two-port coaxial transmission line fixture into which the samples are placed. Among the sample forms that can be fitted into coaxial waveguides are (1) circular disks and (2) annular rings. The former type is sandwiched between two disjointed inner conductors of the coaxial line, whereas the latter dielectric form is snug-fitted to become the insulation layer of an intermediate coaxial section. Each type of sample requires a different coaxial configuration; this work studies both fixtures. The investigation of the first type is based on a previously studied technique that treats the sandwiched circular disk as a parallel-plate capacitor. Because of inaccuracies in the original form of that method, a modified version that offers improved accuracy is devised here. In addition, a new, independently developed technique for accurately characterizing dielectrics of the second form (annular-ring samples) using quadratic curve fitting is proposed. The experimental fixture, comprising a connected series of coaxial waveguide sections, is numerically treated with the method of moments and mode-matching technique. Details of the theoretical groundwork are presented in this paper, which constitutes the first of two parts of this work. Part II, also appearing in this issue, describes the measurement technique in detail and presents simulation results of the experimental procedure based on the formulation presented herein. In addition, the method that treats circular disks is also investigated in Part II and is used to make comparative performance studies.     

A new polyimide film for VLSI and its electrical characterization

Multilevel structures consisting of alternating metal and dielectric layers are necessary to achieve interconnection in high density or VLSI (very large scale integration) circuits using either MOS or bipolar technology. Polyimide is one of the excellent high temperature heat-resistant polymers in organic materials and has good planarization capability and electrical insulating properties. In this work, following the synthesis of DAPDS (4,4'-bis (3-aminophenoxy)diphenyl sulfone), by nucleophilic aromatic substitution of 4,4'-dichlorodiphenyl sulfone with m-aminophenol, DAPDS/pyromellitic dianhydride based soluble and processable fully imidized polyimide was synthesized successfully by using solution imidization technique. Using this specific polyimide, a metal-polyimide-silicon MIS (metal polyimide silicon) structure was manufactured. Electrical properties of the MIS capacitance have been examined. The planarizing and patterning characteristics and electrical characteristics such as current vs. voltage, breakdown field strength, permittivity and capacitance vs. voltage for quasi-static and high frequency measurements are discussed. The results are compared with conventional dielectric films used in integrated circuit fabrication     

Analysis and design of terahertz microstrip antenna on photonic bandgap material

In this paper, a dielectric slab with periodic implantation of the air gaps has been analyzed. An effective dielectric permittivity of the 1-D photonic bandgap substrate material (PBG material) with host material as Polytetrafluoroethylene (PTFE) has been computed at 600 GHz. Based on the extracted effective dielectric permittivity, a rectangular microstrip patch antennas on thin and thick 2-D PBG material as substrate have been designed. The electrical performances of the antennas have been simulated by using two different simulators, CST Microwave Studio based on the finite integral technique and Ansoft HFSS based on the finite element method. This proposed antenna on the PBG material as substrate shows the significant enhancement in the directivity. To validate the homogenized medium approximation, the effect of the antenna position on the substrate material has been observed. The response of antenna has been found to be independent of its position. Various electrical parameters of the proposed antennas have been compared with reported literature. In addition to this, the operating frequency of one of the antenna has been scaled down by the factor of 50 and its various results have been compared with the results obtained at 600 GHz.     

Numerical electric field analysis of capacitance and potential in space for estimation of permittivity distribution

We have been studying on measuring capacitance and potential using long‐distance electrode for estimating a permittivity distribution. The estimating method of permittivity distribution was proposed using finite element method (FEM) and genetic algorithm. However, the measurement accuracy was not reviewed. In this paper, we carried out numerical analysis using FEM in case of change of diameter, position, and permittivity of a rod of dielectric and discussed the measurement accuracy of capacitance and potential.     

折叠Blumlein线的不同结构水电阻负载实验

为了让折叠型平板Blumlein线能得到理想的输出电流电压波形,设计并制作了3种不同结构的水电阻作为折叠型平板Blumlein线的匹配负载,对3种水电阻的电容和电感进行了理论计算和仪器实际测量,使用等效电路法模拟了它们作为折叠线的匹配负载对输出电流电压波形的影响,并在实验中分别得到了相应负载电阻上的电流电压波形。结果表明圆柱形水电阻的电容(2.2 nF)和电感(80 nH)较大,对电流和电压波形的平顶影响最大;扁平形水电阻具有电容较小(0.47 nF)、电感小(25 nH)和散热好等优点,适合作为重复频率同轴Blumlein线的匹配负载;U形水电阻具有电容电感小(0.05 nF,30 nH)的优点,且对波形影响较小,适合作为折叠型平板Blumlein线的匹配负载。     

Analysis and design of rectangular microstrip antenna on two-layer substrate materials at terahertz frequency

In this paper, an effective permittivity of the two-layer dielectric substrate material has been analyzed to enhance the electrical performance of the rectangular microstrip patch antenna at terahertz frequency. The frequency dependent effective dielectric permittivity of the substrate materials has been evaluated and result has been compared with finite integral technique based CST Microwave Studio a commercially available simulator. The input impedance characteristic with electrical performance of the rectangular microstrip patch antenna on two-layer substrate materials has also been analyzed at 600 GHz. Manipulation in the input impedance characteristic of the antenna has led to a slow wave structure. This slow wave structure has been examined at 542 GHz, and improvement in the performance has been observed without increasing the overall dimension of the proposed antenna.     

Method of moments modelling of cylindrical microwave integrated circuits interconnections

In this paper, a numerical technique suitable for characterizing a wide variety of interconnection configurations printed on cylindrical surfaces, is presented. The interconnection lines may have either finite or infinitesimal cross‐sections. To model cylindrical interfaces, suitable space‐domain integral equations are formulated to represent the potential on conductors and electric field at dielectric interfaces. The solution of the integral equations is then obtained numerically by applying the method of moments (MOM). The objective of this approach is to determine the capacitance matrix of cylindrical interconnection systems with different configurations. From the capacitance matrix, other quantities such as characteristic impedance, coupling coefficient and effective permittivity can be determined. The numerical technique described in this paper is implemented as a general computer program. Various circular cylindrical as well as elliptical cylindrical structures have been solved including microstrip lines and coplanar waveguide lines. The results obtained compare very well with other published data. Copyright © 2004 John Wiley & Sons, Ltd.     

220kV电容式电压互感器上节电容介损测量分析

对220 kV电容式电压互感器上节电容单元的介损及电容测量,一直以来采用的是西林电桥正接法10 kV测量方法,这是一种普遍使用的试验方法.但这种测量方法需要将200kV电压互感器上节一次接线拆除,现场拆除引线很不方便.本方法是采用不拆除220 kV电容式电压互感器一次接线,使用去干扰的介损测量反接法,从而避免了繁重的拆...     

基于模量的线路模型识别纵联保护新原理

详细分析了输电线路内、外部故障时故障分量网络的特征,提出可以将线路外部故障等效为电容电路模型,内部故障等效为电感电路模型.基于时域中的短数据窗,利用参数识别的方法,分别计算线路的真实模型与上述2种模型的误差,若电容模型误差小,则判为外部故障;若电感模型误差小,则判为内部故障.对于实际三相线路,为降低相间电磁耦合对模型识别效果的影响,则同时采用线模量和零模量做线路模型识别,从而判断故障.理论分析表明,新方法基于故障分量原理,不受负荷状态和过渡电阻影响,无需补偿电容电流,在时域中进行短数据窗的判据计算,不用滤波提取相量,受暂态分量影响很小.EMTP仿真试验进一步证明了新原理动作可靠、迅速.     

Detection of micron size phantom of biological cell using concentric square ring metamaterial at microwave frequency

ABSTRACT

This paper presents simulation studies and theoretical analysis of sensing property of concentric square ring metamaterial biological materials. Phantom of dielectric cell having dimension 100 µm long and 25 µm in radius is considered. Sensor is designed using periodic arrays of split ring resonators and wires having negative permittivity and permeability at 16.694 GHz. Transmission parameters are extracted using CST MWS software. Change in resonance is observed on placing phantom close to the sensor due to the change in capacitance and inductance. Designed sensor can sense single phantom cell with 133 MHz of shift in resonance. Study shows that sensor has good sensitivity for detecting micron size dielectric objects.     

Thickness dependent ferroelectric properties of BSTO thin films deposited by RF magnetron sputtering

The thickness dependence of ferroelectric permittivity of (Ba, Sr)TiO₃ has been investigated. The BST films could be obtained to have a simple cubic perovskite structure, space group Pm3m, and practically c-axis epitaxial structure deposited at 800^∘C. Through post-annealing process, we have improved the dielectric properties; dielectric permittivity, dielectric loss, and tunability. The change in dielectric properties before and after annealing is attributed to the change in film strain and the contraction in film lattice. As the thickness of BST films increases from 55 nm to 350 nm, the dielectric constant of BST films increases from about 100 to above 670 due to the reduction of interfacial dead layers with low dielectric constant between films and top electrodes. The dielectric loss of BST thin films decreased as the thickness increases. The existence of interfacial dead layers in a thinner film had a larger effect on the effective dielectric constant than tensile strain between the BST films and MgO substrate.     

Low loss flexible SrTiO<Subscript>3</Subscript>/POE dielectric composites for microwave application

Flexible, high dielectric constant and low dielectric loss composites for microwave application fabricated with SrTiO₃ (STO) ceramic filler dispersed inside a thermoplastic polyolefin elastomer (POE) polymer matrix have been studied in this paper. The dielectric property and the mechanical property of STO/POE composites filled with different volume fraction of ceramic filler were investigated. The results indicated that with the increase volume fraction of ceramic filler, both the permittivity and the dielectric loss of composites increased. Good frequency stability within a wide range was observed in all the samples. For the composites containing 40 vol% STO, the composites has a tensile strength of 2.75 MPa with an elongation of about 90% at break value. The permittivity and the dielectric loss of the composites were 11.0 and 0.01 in microwave frequency, respectively. A microstrip transmission line on the composites containing 40 vol% STO as a microwave substrate is designed and measured after bending at different angles, meanwhile the transmission coefficients of the microstrip transmission line were unchanged when bending angle is less than 60°. This indicates that the STO/POE composites have the promising characteristics for potential applications in microwave substrate, flexible dielectric waveguide and related flexible microwave devices.     

QUASI-STATIC MoL-BASED APPROACH FOR THE ANALYSIS OF MULTILAYER TRANSMISSION LINE STRUCTURES

In this paper, a generalized approach for the analysis of multistrip multidielectric layer transmission line structures based on the Method of Lines (MoL) is presented. The proposed algorithm is not limited either by the number of dielectric layers or by the number of metallic strips that can be positioned at different interfaces. The program we have written has been successfully tested on various structures and the obtained results are compared with those published by other authors. © 1997 John Wiley & Sons, Ltd.     

Crosstalk in multilayer printed circuit boards

Experimental measurements were conducted to study the problem of crosstalk in multilayer printed-circuit-board design. Experiments using both pulse and sinusoidal signals were designed to study crosstalk as a function of coupling line lengths, line spacings, and shielding versus nonshielding (lines in different layers). The mutual inductance and capacitance between two similar transmission lines were also extracted from simple models of crosstalk. It is found that when a sinusoid-driven signal was used as the voltage source, the coupled transmission lines acted as a transformer. The induced voltage on the passive line is approximately proportional to the square root of the coupling line length in the range of 2-20 in. These experiments can be used to enhance students' quantitative understanding of the problem of crosstalk in modern electronic circuit design     

Analysis and design of enhanced directivity microstrip antenna at terahertz frequency by using electromagnetic bandgap material

In this paper, an electromagnetic bandgap (EBG) material in the range of 0.5–0.8 THz has been simulated with Arlon AR 600 (ε=6.0) as host material and air‐cylinders as the foreign embedded material. The effective dielectric permittivity of this material has been analyzed at the frequency range of 0.590–0.620 THz. The reduced effective dielectric permittivity substrate of thickness 50 µm has been used to design the microstrip antenna at 600 GHz with a novel approach. This proposed antenna shows an enhanced directivity of 15.1 dBi at 600 GHz frequency. To compare the analysis, the operating frequency has been scaled down by a factor of 100 and various results have been compared by using two different commercially available simulators CST Microwave Studio based on the finite integral technique and Ansoft HFSS based on the finite element method. Copyright © 2010 John Wiley & Sons, Ltd.     

谐振接地系统的新型自动调谐装置

分析了线路对地电容对故障电流负序分量和零序分量的影响以及故障电流负序分量在配电系统中的分布特征,提出了根据接地时刻线路负序电流的相对最大值确定故障线路、根据故障线路负序电流和消弧线圈电流的相位差决定消弧线圈的调节方向、以故障线路负序电流分量的最小值为调节目标的新型综合自动调谐方法.该调谐方法在完成调谐的同时也完成了故障选线,但它并不以正确的故障选线为前提条件,无须测量配电系统的对地电容,也不受配电系统运行方式的影响.即使在故障接地期间改变配电系统的运行方式,该方法也能及时判断并准确调节消弧线圈电感使配电系统重新回到谐振状态.对开发的新型自动调谐装置样机进行了动模实验,结果验证了所提出的方法的正确性和装置的可行性.     

带有径向电极的小尺度电容层析成像传感器设计

电容层析成像应用于小尺度管道内成像的关键问题是传感器的设计，而常规传感器往往无法满足测量需要。该文在分析小管道测量特点后，提出3种不同径向电极布置的小型电容成像传感器结构，并通过有限元仿真比较了不同径向电极布置对测量电容的影响。同时，对电极间绝缘介质介电常数及屏蔽罩与电极外表面距离对电极对间电容的影响进行了详细地探讨。结果表明，对于具有较厚厚度的电极，电极对间的本体电容主要来自电极对侧表面间的电容，且相邻电极间绝缘介质介电常数对电极对间电容的影响不显著，但电极对间电容随着屏蔽罩与电极外表面距离增加而增加。依据仿真结果，设计出一种新型径向电极布置的小尺度传感器，并将其用于实测，获得了较好的结果。     

Feasibility Study on Estimation of Permittivity Distribution by using Genetic Algorithm and Finite Element Analysis

We have investigated a measurement system for permittivity distribution based on the measured capacitance using a pair of large distance electrodes with shield and additional electrodes. However, the estimation of the permittivity distribution has not yet been established. In the paper, we propose a new numerical estimation method based on genetic algorithm (GA) and finite element method (FEM). The gene in the present GA method will have the information on such parameters as the location, radius and relative permittivity of a dielectric. The estimation of capacitance was done by using FEM with the numerical mesh data generated by the information on the gene. We also describe the feasibility of estimation of permittivity distribution using GA and FEM. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.