Input impedance of a circular microstrip disc antenna using mode matching

A model is developed to calculate the input impedance of a coaxially fed circular microstrip disc antenna. A mode-matching approach is used, which makes it possible to include the effects of modes other than the dominant mode. Comparison is made with measured results taken over the frequency range 8 GHz to 11 GHz.     

Analysis and design of periodic structures for microstrip lines by using the coupled mode theory

In this work, the coupled mode theory is formulated to analyze distributed periodic structures for microstrip lines. After it, several reasonable approximations are introduced giving rise to analytical solutions for the problem. The obtained results, both numerical and analytical, are checked against measurements showing very good agreement. The proposed method is very attractive for the study of these devices since it avoids the time-consuming full-wave electromagnetic simulations customarily employed and provides analytical solutions that are very useful for analysis and synthesis purposes.     

Analysis of shielded microstrip lines with arbitrary metallizationcross section using a vector finite element method

The finite element method (FEM) with the high-order mixed-interpolation-type triangular element is used to solve the problem of practical microstrip lines with arbitrary metallization cross section. Analyses are carried out to produce the frequency characteristics of propagation constant, characteristic impedance, and attenuation constant of shielded microstrip lines with rectangular, trapezoidal, and semi-trapezoidal strip cross sections. A comparison of the numerical results with those of the existing results shows good agreement and thus verifies the versatility of the FEM. Also, the numerical results show the effects of the metallization cross sections on the transmission properties and thus emphasize the importance of considering the practical microstrip configurations in the design of miniaturized MMICs     

ANALYSIS OF OPEN MICROSTRIP STRUCTURES BY USING DIAKOPTIC METHOD OF LINES COMBINED WITH PERIODIC BOUNDARY CONDITIONS

This paper presents the analysis of open microstrip structures by using diakoptic method of lines (ML) combined with periodic boundary conditions (PBC). The parameters of microstrip patch are obtained from patch current excited by plane wave. Impedance matrix elements are computed by using fast Fourier transform(FFT), and reduced equation is solved by using diakoptic technique. Consequently, the computing time is reduced significantly. The convergence property of simulating open structure by using PBC and the comparison of the computer time between using PBC and usual absorbing boundary condition (ABC) show the validity of the method proposed in this paper. Finally, the resonant frequency of a microstrip patch is computed. The numerical results obtained are in good agreement with those published.     

Analysis of cylindrical transmission lines with thefinite-difference time-domain method

In this paper, the finite-difference time-domain (FDTD) method is used to calculate the propagation characteristics of cylindrical transmission lines. An efficient two-dimensional FDTD algorithm is developed by projecting the three-dimensional FDTD cell in the cylindrical coordinates onto the r-φ plane. An effective absorbing boundary condition is employed to truncate the mesh at its outer radial boundary. Numerical results are derived for different cylindrical transmission lines and compared to data available in the literature. Specifically, the newly proposed cylindrical coplanar waveguide is studied both theoretically and experimentally     

Analysis of aperture-coupled microstrip antenna using cavity method

Presents an original analysis of aperture coupling of a microstrip antenna. The theory is based on the cavity model, and results are compared with the moment method and measurement.<>     

Analysis of aperture-coupled microstrip antenna using thesegmentation method

The authors present an original analysis of an aperture-coupled microstrip antenna. The theory is based on the segmentation method, which considers the patch as a multiport network whose impedance matrix is deduced from a hybrid matrix, and the use of analytical expressions of the cavity admittance at the slot centre. The theory is presented for the first time, and the theoretical results are in good agreement with previous published measurements     

The studies of cylindrical microstrip line with the FD-TD method in cylindrical coordinate system

In this paper, a full-wave two dimensional Finite-Difference-Time-Domain method in cylindrical coordinate system is developed, in which the arch is chosen as the difference cell. It is proved that the method is efficient and economical in both CPU time and temporary storage requirement, and potentially useful for the numerical analysis of dispersion of cylindrical guidewave structure. the numerical results, including the dispersive curves of the cylindrical single microstrip line and the coupled microstrip line are presented.     

用FE-BI法分析圆柱上共型P波段微带天线

采用有限元／边界元法（ＦＥ－ＢＩ）分析了内嵌在圆柱体上的微带天线,着重讨论了该类天线应采用的基函数和权函数以及柱面单元的编码方法。给出了该类天线在三种不同圆柱半径,辐射单元数目分别为一元、二元时的阻抗特性和辐射特性的理论值和测试值,实测结果与数值结果吻合甚好。     

Spectral and variational analysis of generalized cylindrical andelliptical strip and microstrip lines

The variational technique in the spectral domain (VTSD) is shown to be an efficient method for computing the quasi-TEM parameters of arbitrary multiconductor and multidielectric cylindrical or elliptical strip configurations. Simple conformal mappings reduce the cylindrical or elliptical geometries to an equivalent rectangular one with periodic boundary conditions. The analysis of this equivalent structure is achieved by taking advantage of previous work on boxed planar structures. The numerical convergence of the programs is greatly accelerated, incorporating the asymptotic behavior of the series appearing in the analysis in such a way that efficient programs have been written. It is pointed out that excessively simple approximations to the surface charge distribution yield meaningful numerical errors, mainly when strong coupling or wide strips are involved. As an application example, the behavior of the characteristic parameters of asymmetric coupled structures on multilayer substrates is shown     

Full-wave modeling of via hole grounds in microstrip bythree-dimensional mode matching technique

A rigorous full-wave analysis of microstrip via hole grounds is presented using a three-dimensional mode-matching technique in connection with a suitable segmentation of the structure into homogeneous parallelepipedal cells. The adoption of the novel impressed source technique reduces substantially the numerical effort compared to the transverse resonance technique and, in addition to the finite metallization thickness, accounts for possible package interaction. theoretical results are compared with experimental data from various sources, including the authors' experiments, showing excellent agreement. Package effects have been observed experimentally and shown to be fully predicted by the theory     

Multiple microstrip lines on a multilayered cylindrical dielectricsubstrate on perfectly conducting wedge

The quasi-TEM characteristics of a class of cylindrical microstrip lines are rigorously determined. The class of microstrip lines considered consists of multiple infinitesimally thin strips on a multilayered dielectric substrate on a perfectly conducting wedge. Expressions for the potential distribution inside and outside the dielectric substrate, charge distribution on the strips, and capacitance matrix of the microstrip lines are derived. The problems of a microstrip line on a cylindrically capped wedge and on a cylindrical dielectric substrate on perfectly conducting core are also considered as special cases. Sample numerical results based on the derived expressions are given and discussed     

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].     

Constructing cylindrical panoramic image using equidistant matching

An efficient algorithm for constructing cylindrical panoramic image mosaics from a near pure panning camera is proposed. The algorithm uses equidistant matching for image alignment which uses a translational motion model. It also allows the effective focal length of the camera to be estimated efficiently by a bisection method     

Study of microstrip step discontinuities on bianisotropicsubstrates using the method of lines and transverse resonance technique

A hybrid approach, combining the method of lines (MoL) and transverse resonance technique (TRT), is presented for the analysis of microstrip step discontinuities that are printed on uniaxial or biaxial bi-anisotropic substrates. The method of lines, formulated in terms of Kronecker products, is used to determine the characteristic equation for the resonant length. The transverse resonance technique is applied to obtain the S-parameters of the junction by casting the discontinuity problem as a microwave equivalent network. Good agreement is found between results of the MoL/TRT approach and those obtained by other methods. Effects of individual tensor elements of the substrate on the scattering parameters of the discontinuity are investigated at selected frequencies. The proposed MoL/TRT approach is found to converge very fast and does not require excessive computer memory, with all computations performed on a 486DX-50 MHz PC     

A compact branch-line coupler using discontinuous microstrip lines

We introduce a branch-line coupler using discontinuous microstrip lines whose size is significantly reduced relative to the standard design. We manipulate the reactive characteristics of discontinuities in its microstrip lines to achieve a physical size reduction of almost 60% with comparable performance.     

Analysis of microstrip patch antennas using finite difference timedomain method

The study of microstrip patch antennas is directly treated in the time domain, using a modified finite-difference time-domain (FDTD) method. Assuming an appropriate choice of excitation, the frequency dependence of the relevant parameters can readily be found using the Fourier transform of the transient current. The FDTD method allows a rigorous treatment of one or several dielectric interfaces. Different types of excitation can be taken into consideration (coaxial, microstrip lines, etc.). Plotting the spatial distribution of the current density gives information about the resonance modes. The usual frequency-dependent parameters (input impedance, radiation pattern) are given for several examples     

Analysis of elliptical and circular microstrip antennas using moment method

A method of calculating the input impedance of either a circular or a slightly ellipitcal microstrip antenna excited by a coaxial probe is presented. Using the reaction integral equation and the exact dyadic Green's function, the finite substrate thickness is taken into account in the formulation. Good agreement with experimental results for an elliptical patch is obtained and a design procedure for a circularly polarized antenna is presented.     

Varactor-tuned combline bandpass filter using step-impedance microstrip lines

In this paper, a varactor-tuned combline bandpass filter using step-impedance microstrip lines is considered so that the absolute passband bandwidth can be maintained nearly constant within the tuning range. The difference between the odd- and even-mode characteristics of the coupled microstrip line makes it difficult to design a tunable bandpass filter with minimum degradation in passband performance. By using step-impedance microstrip lines, couplings between resonators can be controlled so that the constant bandwidth requirement could be satisfied with reasonable design parameter values. Lumped inductors are used for input and output coupling networks. Design equations are derived, and experimental results are compared with theoretical ones based on these equations.     

Network analysis of microwave oscillators using microstrip transmission lines

A network and computer-aided-design approach is discussed which is useful in designing microstrip oscillators to operate between 10 and 20 GHz. The analysis is applied to GaAs m.e.s.f.e.t. active devices.