Optimum Impedance and Dimensions for Strip Transmission Line

This paper makes use of the higher mode limitations on the dimensions of symmetrical strip transmission line to derive the permissible dimensions at any given frequency and characteristic impedance. In conjunction with Cohn's results for the attenuation in strip transmission line these are used to obtain the maximum achiew able Q at any frequency and the optimum characteristic impedance; that is, the impedance providing the lowest attenuation. This provides the basis for selecting the characteristic impedance for resonant elements in strip line filters and other applications wherein the lowest possible attenuation is desired. Conclusions are also reached regarding the best form factor (ratio of strip thickness to ground-plane spacing) for a given characteristic impedance.     

Characteristic Impedance of the Shielded-Strip Transmission Line

Simple formulas are given for the characteristic impedance of a transmission line consisting of a conducting strip of rectangular cross section centered between parallel conducting plates at ground potential. The formulas agree to within 1.2 per cent with an exact formula for a zero thickness strip. In the case of finite thickness up to a quarter of the plate spacing, the formulas are expected to be at least that accurate. A family of characteristic impedance curves given in this paper should prove useful to the design engineer.     

Stopband-enhanced and size-miniaturized low-pass filters using high-impedance property of offset finite-ground microstrip line

The uniform finite-ground microstrip line (FGMSL) and its constituted circuit elements are thoroughly characterized via self-calibrated method of moments for innovative design of a stopband-enhanced and size-miniaturized low-pass filter (LPF). Firstly, an offset FGMSL is modeled and extracted to quantitatively exhibit its capacity in achieving higher characteristic impedance compared to the infinite-ground microstrip line (MSL) counterpart. Secondly, the finite-extended FGMSL section with equally widened strip/ground or offset narrow strip/ground conductors is studied in terms of an equivalent T- or /spl pi/-network, thereby constructing the modified MSL shunt capacitive or series inductive element. By making effective use of enlarged series inductance of an offset FGMSL with shorter electrical length, two novel LPF blocks are designed on a basis of cascaded circuit networks. Predicted S-parameters show widened and deepened stopband beyond the low passband. Furthermore, it is confirmed by measurement.     

射频连接器与微带线组件焊接过渡段阻抗补偿研究

射频连接器与微带线组件常用于通信系统电路中,而组件焊接过渡段的阻抗不连续会使电路中的信号损耗增大.针对该问题,本文对射频连接器与微带线组件焊接过渡段进行研究,基于传输线理论,建立焊接过渡段的等效电路模型.讨论了焊接过渡段特征阻抗不连续的原因,同时提出了补偿优化方案.此外,通过电磁场与电路的联合仿真,提取出补偿前后等效电路模型的电参数,从等效电路模型的角度分析了补偿方案对组件过渡段复杂电磁特性的影响.有限元仿真分析与实验测试结果显示,补偿后组件的性能显著提高,证明了补偿方案有效可行.     

Capacity and Characteristic Impedance of Strip Transmission Lines with Rectangular Inner Conductors

An example of the rigorous solution of a complex region boundary value problem is presented. The particular problem, the electrostatic capacity and characteristic impedance of a strip transmission line, is solved exactly and numerical results are given for a particular geometrical configuration.     

Wire and strip conductors over a dielectric-coated conducting ordielectric half-space

The complex wavenumber and characteristic impedance are determined for a wire or flat strip over a dielectric-coated half-space that can be a conductor or a dielectric with large permittivity. Elevated microstrip is an example of the configuration. The properties of the wire as an antenna or transmission lines are determined from those of the insulated antenna with a two-layer eccentric insulation. The theory is extended to the strip conductor with the help of a comparison of the tubular and strip conductors over a perfectly conducting half-space     

正方外导体-微带内导体传输线特性阻抗严格解

应用保角变换法,严格推导出正方外导体一单一微带、“十”字微带和耦合微带内导体传输线特性阻抗精确表达式,并给出了不同参数条件下传输线特性阻抗的数值结果。     

Impedance of a transverse slot in the ground plane of an offset stripline

A generalized formulation for the determination of the impedance of a transverse slot in the ground plane of an offset stripline is presented. The results of the analysis are used to compute the variation of slot impedance with strip offset and also with change in position of one of the ground planes. Comparison of the theoretical results with experimental data is presented.     

Computation of the Characteristics of Coplanar-Type Strip Lines by the Relaxation Method (Short Papers)

The characteristics of new strip lines (i.e., a single strip conductor and a two symmetrical strip-conductor coplanar-type strip line, which consist of single- or two-center strip conductors and ground plates on a dielectric substrate and outer ground conductor) are calculated by the relaxation method. The effect of the outer ground conductor on these lines is analyzed, and the characteristic impedance and velocity ratio are determined. The characteristic impedance is determined experimentally, and the maximum values of the discrepancies compared with the calculated values of each of the lines are 2.0-3.0 percent.     

Discontinuities in Symmetric Striplines Due to Impedance Steps and Their Compensations

The theoretically known magnitude of the series lumped reactance, as a function of impedance step ratio, resulting from an impedance step discontinuity in symmetric stripline is confirmed, and an alternative expression for the inductance is given. A reduction of this reactance has been achieved by splitting the narrower strip at the impedance step junction into a multistrip configuration, while retaining the total characteristic impedance value. A way of compensating the effect of the reactance on the pass-band characteristics of quarter-wave impedance transformers and filters is developed. This is achieved by the introduction of a lumped series capacitance at the impedance step discontinuity.     

Coupled Strip Transmission Lines with Rectangular Inner Conductors

A method is presented for determining the capacitance of electrostatic fields which have hitherto proved intractable because their solutions required the evaluation of hyperelliptic integrals. The method is illustrated by applying it to the determination of the characteristic impedance of a strip transmission line. The results compare favorably with the results of existing solutions. The method is then used to determine the characteristic impedance of coupled strip transmission lines with inner conductors of rectangular shape. Curves are included which permit the determination of this impedance over a wide range of line proportions.     

Application of grooved substrates for design of unequal wilkinson power dividers

Application of the grooved substrate is presented for the design of an unequal Wilkinson power divider. The grooves are applied along one of its strips which requires high characteristic impedance for the purpose of overcoming its conventional narrow width. The grooves are oriented parallel to the strip and just next to it. The groove depths are selected such that, for a suitable width of the strip, the desired characteristic impedance is achieved. A 4:1 unequal Wilkinson power divider is designed, fabricated and tested, which verify the design specification of power division.     

A general analysis of propagation along multiple-layersuperconducting stripline and microstrip transmission lines

A rigorous spectral-domain formulation for a superconducting stripline or microstrip transmission line with a multiple-layer dielectric substrate is presented. The formulation models the strip conductor as a surface current with an equivalent surface impedance, where the surface impedance is approximated in closed form when the strip is either much thinner or much thicker than a penetration depth. In either case the surface impedance is related to the complex conductivity of the material, which is calculated from a two-fluid model. Results are presented to show the slow-wave propagation and attenuation along both microstrip and stripline packages in a realistic multiple-layer configuration, which accounts for the field penetration into the superconducting ground planes     

Plane wave diffraction by a slit in a perfectly conducting plane and a parallel complementary strip

The diffraction of plane electromagnetic waves by the configuration formed by a slit in a perfectly conducting plane and a parallel complementary strip is investigated. The related boundary-value problem is formulated into a modified matrix Wiener-Hopf equation. The factorization of the kernel matrix is accomplished through Abrahams’ method and the modified matrix Wiener-Hopf equation is first reduced to a pair of coupled Fredholm integral equations of the second kind and then solved by iterations. Several numerical results illustrating the effects of various parameters such as the spacing between the slit and the strip and their width on the diffraction phenomena are presented.     

Characteristics of a novel biaxial capacitive MEMS accelerometer

A novel MEMS accelerometer with grid strip capacitors is developed.The mechanical and electrical noise can be reduced greatly for the novel structure design.ANSOFT-Maxwell software was used to analyze the fringing electric field of the grid strip structure and its effects on the designed accelerometer.The effects of the width,thickness and overlapping width of the grid strip on the sensing capacitance are analyzed by using the ANSOFT-Maxwell software.The results show that the parameters have little effect on the characteristics of the presented accelerometer.The designed accelerometer was fabricated based on deep RIE and silicon-glass bonding processes.The preliminary tested sensitivities are 0.53 pF/g and 0.49 pF/g in the x and y axis directions,respectively.A resonator with grid strip structure was also fabricated whose tested quality factor is 514 in air,which proves that the grid strip structure can reduce mechanical noise.     

Development of a Cavity-Backed Broadband Circularly Polarized Slot/Strip Loop Antenna With a Simple Feeding Structure

A cavity-backed loop antenna is developed for producing broadband circularly polarized (CP) radiation. The antenna configuration consists of a slot loop and a strip loop. The slot loop radiates a CP wave at a lower frequency while the strip loop produces CP radiation at a higher frequency. A combination of the two frequencies leads to a bandwidth enhancement. The slot/strip loop antenna is fed by a single straight microstrip line. It is demonstrated that the cavity-backed slot/strip loop antenna can achieve an axial ratio (les 3 dB) bandwidth of 19% with good impedance matching. The antenna configuration is described and the operating principles for broadband circular polarization and impedance matching are analyzed. The antenna performance is confirmed by experimental results.     

超高频射频识别近场系统互耦效应中频率偏移研究

在超高频射频识别(UHF RFID)系统近场(NF)密集标签应用中,由于微带标签天线的结构特点,传统线圈间互阻抗表达式在预估系统频率偏移等互耦效应问题方面误差较大,精确性不够。首先,基于变压器模型,从无线电能传输的角度推导了近场密集标签间的互阻抗表达式。然后,结合近场电感耦合型标签,通过建立电磁仿真模型间接获取有关电气参数值。最后,验证推导公式并从影响双标签间互阻抗的环境因素角度去研究UHF RFID近场频率偏移问题。测试结果表明,当标签间距小于30 mm时,推导的互阻抗表达式应用于频率偏移计算误差范围为1.6～7.3 MHz。研究结果为基于标签间互阻抗预估UHF RFID近场标签间的互耦效应问题提供了参考依据。     

Computation of Coplanar-Type Strip-Line Characteristics by Relaxation Method and its Application to Microwave Circuits

The characteristics of new strip lines [i.e., a single strip-conductor coplanar-type strip line (S-CPS), a two symmetrical strip-conductor coplanar-type strip line (T-CPS), and a coupled strip-conductor coplanar-type strip line (C-CPS), which consists of single two-center strip conductors or coupled strip conductors and ground plates on a dielectric substrate and outer ground conductor] are calculated by the relaxation method. The effect of the outer ground conductor and side wall on these lines is analyzed and the characteristic impedance and phase-velocity ratio are determined. The characteristic impedance is determined experimentally and the maximum values of the discrepancies compared with the calculated value of each of the lines are 2.0-3.0 percent. Application examples of the coplanar-type strip line to microwave transistor amplifier and parallel-coupled filter are shown. A transistor amplifier of small size, light weight, wide bandwidth, and improved reliability is achieved. A parallel-coupled filter small in size (reduction ratio is more than 50 percent), with good frequency symmetry and featuring easy resonance frequency fine tuning is obtained.     

Characteristic impedance of stripline

In the letter a simple correction for the influence of the strip thickness on the characteristic impedance of stripline is proposed. This correction is intended for use with Wheeler's formula for characteristic impedance. The thickness correction is independent of strip width and thus has to be calculated only once. The formulas are extremely simple, and can easily be evaluated with a calculator.     

On the modeling of metal strip antennas contiguous with the edge ofelectrically thick finite size dielectric substrates

A solution to the problem of radiation by a narrow metal strip antenna contiguous with the edge of a dielectric substrate is presented where the substrate has parameters such that its electrical thickness is appreciable. Such an antenna may be useful at millimeter wavelengths as an integrated phased array element forming a part of a monolithic microwave integrated circuit (MMIC). A suitable geometry for this application is illustrated and an efficient computational procedure developed. Comparisons with experimental results for the input impedance and far-field radiation patterns show excellent agreement. The influence of the dielectric substrate on the performance of an antenna designed to operate at approximately 60 GHz is discussed. Two examples, the first involving the analysis of a coplanar strip transmission line fed antenna and the second involving impedance matching and control of cross-polarized radiation using a folded strip dipole, are given to illustrate practical applications of the analytical method to design problems