Full-Wave Analysis of Inside Cylindrical Microstrip Lines by Finite Element Method

In this paper, a full-wave analysis using finite element method is presented to investigate the dispersion characteristics of inside cylindrical microstrip lines, which are essential to the design of some conformal microstrip circuits in millimeter wave bands. Numerical results of frequency-dependent effective dielectric constants are given for different structural dimensions and dielectric constants of substrate. Some useful conclusions are derived for the design of the special conformal microstrip lines.     

A New Microstrip Dispersion Model (Short Papers)

A new unified analysis technique is presented for dispersion in microstrip at high frequencies. The technique exploits the fact that the dispersion in microstrips is due to coupling between a surface-wave mode and the LSE mode of an appropriate model of the microstrip. The analysis uses an effective dielectric constant (EDC) approach to evaluate the mode coupling in the LSE model. Unlike previously reported models, all the parameters of the model are exactly determined from the quasistatic parameters of the microstrip, which takes the fringing field into account. Approximate closed-form equations are derived for the prediction of microstrip dispersion. The results agree within 1.50 percent with the experimental and previously published data over a wide useful range of microstrip dimensions and substrate permittivities.     

Dispersion data for open inverted microstrip on RT-duroid and fused quartz substrates

Accurate dispersion data for open inverted microstrip is presented. Two most commonly used substrate materials, namely, RT-duroid (dielectric constant 2.22) and fused quartz (dielectric constant 3.78) are considered. The work is a continuation of the earlier reported data on a similar structure, called suspended microstrip, and will be an useful addition to the millimeter-wave designer's library.     

A tapped-delay-line superconductive chirp filter in shieldedmicrostrip

A superconducting chirp filter having a dispersive time delay of 26 ns and a 3.4-GHz bandwidth centered at 4.7 GHz has been fabricated using a niobium-on-silicon shielded microstrip technology. Along a 2×1.6 m delay are, unequally spaced microstrip directional couplers ire employed as sampling devices. To achieve an improvement in dispersion and coupler directivity over conventional microstrip, the device uses a superconductive shield mounted at a distance equal to the height of the dielectric on top of the microstrip structure. Structural support of the 70-μm-thin high-resistivity dielectric is provided by a large-area bond to a glass substrate     

Losses of Microstrip Lines

This article summarizes state-of-the-art information on losses of single and coupled microstrip lines. Conductor loss, substrate loss (for pure dielectric or magnetic materials), and radiation loss are considered along with the effect of dispersion. Finally, a rough comparison is made between the losses of microstrip and that of several other types of lines used in microwave integrated circuits.     

Dispersion in Microstrip (Correspondence)

An empirically derived equation is given which describes the apparent variations of /spl epsiv//sub eff/ with frequency in microstrip transmission lines for a wide range of dielectric constants and w/h ratios. The equation demonstrates the relation between dispersion and substrate thickness.     

基于Polys try介质基板微带天线的应用研究

针对传统贴片天线检测频率有限(2~35 GHz)且由于增益低导致检测结果不明显的问题,文中提出了以聚苯乙烯作为介质基板构建微带天线的解决方案。在以介电材料玻璃超细纤维为介质基板的理论基础上,采用高分子材料Polysty作为介质基板构建微带天线模型。结合经典天线理论计算辐射贴片以及介质基板尺寸;基于HFSS搭建Polysty作为介质基板的模型并根据微带天线特性将理论设计的微带天线参数进行优化,最终得到在1 GHz时微带天线的最佳尺寸。仿真及实验结果表明,Polysty作为介质基板的微带天线中心频率可以达到1 GHz,增益高并且检测角度范围大。     

Picosecond pulse propagation in coplanar waveguide forwarddirectional couplers

The spectral-domain method is used to calculate the frequency-dependent even- and odd-mode effective dielectric constants of symmetric coplanar waveguide forward directional couplers. Comparisons are made with symmetric microstrip forward couplers on the same substrate that have the same line spacing and access port characteristic impedance. Results are shown which indicate that certain coplanar designs will have lower loss and greater bandwidth than the microstrip devices. Picosecond pulse propagation in both structures is studied using the calculated dispersion data     

屏蔽微带线特性的谱域导抗法分析

本文用谱域导抗法分析了微带线的特性,研究了屏蔽盒对微带线传播特性和色散特性的影响。 谱域导抗概念的引入大大简化谱域方法中冗长的场公式推导过程,其分析结果又能保证相当高的精度。本文 的研究结果表明:屏蔽盒的顶盖使微带线等效介电常数变小,对色散特性影响不大;屏蔽盒的侧壁使微带线 等效介电常数变大,并减小了微带线的色散.     

Micromachined W-band filters

Results are presented for high performance planar W-band filters based on silicon micromachining techniques common in microsensor fabrication. Two types of micromachined planar transmission lines are studied: microshield line and shielded membrane microstrip (SMM) line. In both of these structures, the conducting lines are suspended on thin dielectric membranes. These transmission lines are essentially “floating” in air, possess negligible levels of dielectric loss, and do not suffer from the parasitic effects of radiation and dispersion. A 90 GHz low pass filter and several 95 GHz bandpass filters are tested and display excellent performance which cannot be achieved with traditional substrate supported circuits in CPW or microstrip configurations. A full-wave finite-difference time-domain (FDTD) technique verifies the measured performance of the W-band circuits and provides a basis for comparison between the performances of membrane supported circuits and equivalent substrate supported circuits