Quasi-analytical static solution for the generalized boxed coplanar waveguide

A quasi-analytical method for computing the quasi-static-TEM parameters of the generalized coplanar waveguide (GCPW) is reported. The structure is assumed to be enclosed in a rectangular frame and embedded in a layered medium. Essentially, the method is an analytically enhanced spectral domain formulation. Its application leads to virtually exact results in very short CPU times, making it suitable for CAD purposes. Although the method is somewhat more time consuming than conformal mapping approaches, it is a useful alternative because of its exactness and ability to deal with multilayer structures. © 1994 John Wiley & Sons, Inc.     

Spectral domain analysis of conductor losses in a multiconductorsystem via the incremental inductance rule

Spectral domain analysis is adapted to analyse the conductor losses of a multiconductor system embedded in a multilayered medium using a quasi-TEM approach and assuming a strong skin effect. After adapting the incremental rule to a multiconductor system, the conductor losses are computed in terms of the derivative of the inductance matrix     

Generalized spectral analysis of planar lines on layered mediaincluding uniaxial and biaxial dielectric substrates

The spectral-domain analysis is generalized to compute the dispersive properties of a wide variety of planar and quasiplanar transmission lines (microstrips and finlines) printed on a stratified dielectric medium. Uniaxial and biaxial dielectric anisotropy can be easily manipulated due to the definition of a transverse propagation matrix characterizing each dielectric layer. The whole boundary value problem is reduced to two simpler problems involving only one or two dielectrics, and the spectral dyadic Green's function is derived by a recurrence algorithm. The dispersion equation is derived by using the Ritz-Galerkin method. The numerical convergence is substantially improved taking into account the asymptotic behavior of the series. A number of illustrative examples are included to emphasize the power of the method     

On the fast approximation of Green's functions in MPIE formulationsfor planar layered media

The numerical implementation of the complex image approach for the Green's function of a mixed-potential integral-equation formulation is examined and is found to be limited to low values of κ_oρ (in this context κ₀ρ = 2πρ/λ₀, where ρ is the distance between the source and the field points of the Green's function and λ₀ is the free space wavelength). This is a clear limitation for problems of large dimension or high frequency where this limit is easily exceeded. This paper examines the various strategies and proposes a hybrid method whereby most of the above problems can be avoided. An efficient integral method that is valid for large κ₀ρ is combined with the complex image method in order to take advantage of the relative merits of both schemes. It is found that a wide overlapping region exists between the two techniques allowing a very efficient and consistent approach for accurately calculating the Green's functions. In this paper, the method developed for the computation of the Green's function is used for planar structures containing both lossless and lossy media     

An efficient numerical spectral domain method to analyze a largeclass of nonreciprocal planar transmission lines

Presents an efficient numerical application of the Galerkin method in the spectral domain (SD) to the analysis of striplike/slotlike coplanar transmission lines embedded in a bianisotropic multilayered medium. The method is based on obtaining the spectral dyadic Green's function by the equivalent boundary method (EBM), a suitable third order extraction technique of the asymptotic behavior of the Green's dyad, an enhanced numerical integration scheme, and the use of an adequate contour integral method for searching zeros in the complex plane. This method, namely the SD-EBM, has been found to be very suitable for analyzing transmission lines with semiconductors and/or ferrites magnetized at an arbitrary direction, including the study of magnetostatic wave propagation phenomena     

Efficient spectral domain analysis of generalized multistrip linesin stratified media including thin, anisotropic, and lossy substrates

The full-wave analysis of multiconductor microstrip lines used in electooptic modulators (EOMs), MMICs, or high-speed VLSI applications is addressed. An arbitrary number of coupled coplanar strips are embedded in a stratified medium involving iso/anisotropic dielectric and/or semiconductor layers. The numerical aspects of the computation of the propagation constants using spectral domain analysis (SDA) are stressed. An efficient scheme is used to accurately compute attenuation and propagation constants and current distributions with reasonable CPU times. Convergence problems due to the existence of very thin layers adjacent to the metallized interface have been explicitly considered. An algorithm for computing the modal characteristic impedances regardless of the number and nature of substrate layers is provided. A reciprocity related definition of modal impedances is used to ensure the symmetry of the multiport scattering matrix associated with the structure     

Experimental chemotherapy. II: Study of the cytomorphologic effects of radiation and antitumor chemotherapy on neoplastic tissue

The authors study the effects of MTX, 5-FU and cyclosphosphamide on cell morphology in several human genital neoplasms growing in chick embryo chorioallantoic membrane, comparing them with the cell alterations observed in homologous tumors in cancer patients treated by radiation therapy.     

APPLICATION OF THE NETWORK METHOD TO HEAT CONDUCTION PROCESSES WITH POLYNOMIAL AND POTENTIAL-EXPONENTIALLY VARYING THERMAL PROPERTIES

Nonlinear transient heat conduction in a finite slab with potential-exponential temperature-dependent specific heat and thermal conductivity is investigated numerically by using the network method. A general network model for this process is proposed, whatever the exponent of the temperature-dependent functions may be, including initial and boundary conditions. With this network model and using the electrical circuit simulation program PSPICE, time-dependent temperature and heat flux profiles at any location can be obtained. This approach allows us to solve this conduction problem by a general, efficient, and relatively simple method. To show the accuracy of the network method, a comparison is made of the present results and those obtained by other methods for a particular case.     

Quasi-analytical static solution of the boxed microstrip lineembedded in a layered medium

A quasi-analytical method to carry out the quasi-TEM study of a microstrip line embedded in a general layered substrate with rectangular enclosure is presented. Electric walls, magnetic walls, and periodic boundary conditions are considered. The analysis is based on the spectral-domain formulation and the use of a proper expansion of the free charge distribution (Chebyshev polynomials with edge condition). Two different approaches are proposed to speed up the evaluation of the spectral series in such a way that only a few spectral terms must be retained in the numerical computations of the mentioned series. The propagation parameters and the charge distribution are obtained with extreme accuracy in fractions of one second on a personal computer     

Quasi-TEM analysis of reciprocal/nonreciprocal planar lines with polygonal cross-section conductors

Multilayered multiconductor transmission lines with polygonal cross-section-perfect conductors are analyzed under a quasi-TEM approach. According to a model previously proposed by the authors, each polygonal cross-section conductor is modeled as a set of zero-thickness strips. The substrates can be lossy, and present possible gyromagnetic (longitudinal magnetization) characteristics as well as dielectric anisotropic properties. The method of moments of Galerkin is applied in the spectral domain to analyze the model structure. Special attention has been paid to the fast and accurate computation of spectral integrals. Thus, the possible symmetries of the Galerkin matrix are emphasized and recurrence formulas to compute the tail integrals have been developed. © 1994 John Wiley & Sons, Inc.