Dispersion characteristic of a microstrip line with a step discontinuity

The t.l.m. method of numerical analysis in three space dimensions and time has been successfully applied to microstrip problems. In the letter, a general discontinuity problem in the form of an abrupt change of width in a microstrip line is analysed and comparison is made with approximate data in the literature.     

Analysis of a double step microstrip discontinuity in the substrateusing the 3D-FDTD method

The finite-difference time-domain (FDTD) method has been applied to the analysis of a double step microstrip discontinuity having thickness changes in the longitudinal direction. The discontinuity occurs in patch antenna feeds or interconnections between microwave planar circuit modules. The simulation results are compared with those computed by HFSS to show a good agreement. An equivalent circuit for the double step discontinuity is developed from the scattering parameters computed by the FDTD method     

An experimental investigation of the microstrip step discontinuity

A simple, inexpensive technique for performing wideband (multidecade) validation measurements is introduced. The authors emphasize scaling the desired validation frequencies and dimensions so that both the measurement and the fabrication can be performed accurately and inexpensively. The utility of a composite structure (rather than a single discontinuity) is also demonstrated, and the sensitivity of the structure to changes in the discontinuity is checked. The technique allows an inexpensive validation to be performed which previously could be realized only with large scatter, if at all     

Transient analysis of dielectric step discontinuity of microstrip lines containing a nonlinear layer

Tansient signal propagation characteristics through step discontinuities on microstrip lines with nonlinear substrate are presented. In the proposed model structure, the transient electromagnetic wave propagates from microstrip line with linear substrate to one with nonlinear substrate or vice versa, where two structures are connected to create abrupt discontinuities. The distortions of transient signal through this two abrupt discontinuity structures are numerically simulated by three dimensional FD-TD method. Results show that the distortions of transient signal are evidently influenced by the density of electric field propagating along the microstrip line with nonlinear substrate.     

Modelling microstrip step discontiuities by the transmission matrix

The transmission matrix is applied to characterise general microstrip step discontinuities based on the waveguide model. Considerably more CPU time can be saved compared to the scattering matrix.     

宽频带微带传输线巴伦的研究

对具有宽频带特性的微带传输线巴伦进行了研究,并应用微波网络优化理论对其进行了详细的理论分析与设计,数值计算结果与有关文献一致。最后,设计并制做了具有十倍频程的微带传输线巴伦,举例说明了本文方法的有效性。     

Compact microstrip bandpass filter with two transmission zeros using a stub-tapped half-wavelength line resonator

A compact microstrip bandpass filter is developed using a half-wavelength (/spl lambda//2) transmission line resonator with a pair of tap-connected open-ended stubs. Such paired stubs with total length of about /spl lambda//2 constructs an equivalent line resonator. Together with two separated /spl lambda//4 line resonators, the three transmission poles can be achieved inside the passband. Meanwhile, two stub lengths are adjusted slightly longer and shorter than /spl lambda//4 to realize the two transmission zeros at both low and high rejection bands. Further, the long tapped-stub is kept wider than its short counterpart to improve the low rejection behavior. A filter sample is designed and fabricated to provide an experimental verification on the proposed filter.     

A density-independent method for high moisture content measurement using a microstrip transmission line.

This paper describes a method to measure high moisture content in materials from 190% to 350% on a dry weight basis. The method uses a microstrip transmission line, on which the material under test is overlaid. A parameter calculated from the attenuation and phase shift of the microwave signal is proposed to measure the moisture content. The experiments were performed on samples of sawdust, and the results show that the method is able to determine high moisture content independent of density. The standard error of calibration for the moisture content determination was 12.4% in the moisture content range from 190% to 350%.     

Decoupling between two conductor microstrip transmission line

A numerical analysis of two-conductor transmission line with a rectangular notch in the dielectric between the strips is presented. Three media integral equations are derived and solved for the charge distributions. The decoupling between such two-conductor coupled microstrip transmission lines is investigated for asymmetric conductors. It is found that the coupling between two conducting lines can be reduced significantly by removing dielectric material between the lines which has a rectangular shape. For best decoupling, the width should be as wide as possible between the conducting lines but the depth should have an optimum somewhere in the base dielectric substrate     

Analysis of inclined microstrip patch antenna using enhanced FDTD equations

Using the enhanced FDTD equations for diagonal metal edges, a rectangular microstrip patch, inclined to the grid by 45/spl deg/, has been analysed. The enhanced equations give extremely accurate results even with a coarse grid. The accuracy of the first resonance frequency obtained using the enhanced equations was 1.1%, compared to 7.1 and 3.5% using the staircase and split-cell models, respectively.     

基于左手传输线的双线极化微带阵列天线

基于左手传输线,提出了一种新型串联馈电的双线极化微带阵列天线结构.通过上层微带线边馈和下层小孔耦合馈电的方式分别实现了天线单元的垂直极化和水平极化的激励,进而使得该天线单元具有高极化隔离度、低交叉极化和宽频带工作等优点.同时由于左手材料具有相位超前的特性,利用传统的右手微带传输线和左手微带传输线的组合以达到零相位延迟,实现了对上述单元构成的微带阵列天线的串联馈电.相对于传统微带阵列天线,该阵列天线结构简单、面积小、插入损耗小、阵列效率高、易于扩展成更大的平面阵列.     

Design of microstrip hyperbolic line to match a complex impedance to a standard coaxial transmission line

Based on the solution of the Riccati equation, a hyperbolically tapered microstrip transmission line for matching a complex load to a standard coaxial cable is designed. An iterative procedure is used to yield the phase constant leading to an accurate design. A numerical example is considered. The result shows that a tremendous reduction in the size of matching components can be achieved if hyperbolic instead of uniform transmission lines are used. This is highly advantageous in the miniaturization of solid state circuits.     

基于ADS的微带线不连续性分析与应用

射频电路印制电路板（PCB）中出现的微带线拐角是微带线不连续结构之一,而微带线的不连续性会影响信号传输质量。为降低微带线不连续性对信号传输质量的影响,利用ADS（Advanced Design System）软件对不同拐角进行仿真,从两个角度分析了它们对电路性能的影响。在此基础上,将研究结果应用于5.8 GHz RFID（Radio Frequency Identification）阅读器射频电路中,取得了较为理想的效果。结果表明：45°外斜切直角拐角和圆弧拐角均能对传输线的不连续性进行补偿,其中,45°外斜切直角拐角存在最佳斜切率M,使拐角处信号的传输特性（即回波损耗和插入损耗）最优。该研究对降低微带线不连续性对信号传输质量的影响具有一定的指导意义。     

The new method of time-domain analysis of a planar transmission line with discontinuity

In this paper, the new technique of time-domain analysis of discontinuities in a planar transmission line is presented. In the process of time-domain analysis, the analysis model of system and the concept of transfer function are employed and the frequency-domain method of lines and the technique of the fast Fourier transform are used. The results of time-domain data and frequency-domain characteristics for the shielded microstrip with step discontinuity are given and compared with the published results of other authors.     

On the double nature of transmission zeros in microstrip structures

The EM nature of transmission zeros in microstrip structures has been the subject of several discussions. A liquid crystal thermal mapping technique is used for detecting the magnetic field distribution inside rectangular structures at the frequencies of the transmission zeros. In this way a perceptible evidence is given to previous theoretical results, which have pointed out the existence of two types of transmission zeros, called modal zeros and interaction zeros.     

Pole discontinuity removal using artificial neural networks for microstrip antenna design

This article presents the use of artificial neural networks for the evaluation of integrals with finite number of pole singularities while formulating the integral equation for the electric surface current density. A feed-forward single-layer back-propagated artificial neural network (ANN) model has been trained to approximate the discontinuous integrand function. Generation of a soft continuous function obtained from the ANN model and closed-loop expressions for the evaluation of the integrals are presented. The proposed technique is applied to compute the input impedance of microstrip antenna and results have been compared with IE3D. Integration has been performed using n-point Gaussian quadrature rule for evaluating the reaction matrix.     

Analysis of transmission line structures using a new image-modeGreen's function

A hybrid image-mode-moment method for the quasi-transverse-electromagnetic (quasi-TEM) analysis of transmission lines of arbitrary cross section and number, suspended between infinite parallel ground planes is discussed. This method systematically combines, in a single formulation, the conventional moment method with a new image-mode Green's function. The moment method is used to model the interaction between transmission lines, and the new image-mode method is used to furnish the Green's function of the parallel plates. Several configurations are studied and compared, where possible, with work given in the references     

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].     

Compact left-handed microstrip line based on multiple layered step impedance resonators

A novel compact left-handed (LH) microstrip transmission line is presented. To establish a negative permeability and permittivity, the transmission line is loaded with step impedance resonators (SIRs) and an array of thin wires on dual-layer architecture. Compared to existing LH structures, which incorporate conventional split ring resonators (SRRs), the proposed structure is three times smaller in size whilst achieving the same performance. To illustrate the electromagnetic properties of the metamaterial, both analytical and full wave analysis were performed and utilized to determine the effective electromagnetic parameters of the proposed structures. The experimental results show that a microstrip line periodically loaded with SIR only produces a rejection of ?6?dB at a resonant frequency of 5.50?GHz. The results also indicate a pass-band response for a left-handed microstrip line (LHML) constructed from SIR and thin wire arrays at the same resonant frequency.