Thinh Q. Ho

Spectral-domain analysis of shielded microstrip lines on biaxially anisotropic substrates

The spectral-domain technique is extended to the study of shielded microstrip lines on biaxial substrates. The analysis simultaneously includes dielectric and magnetic anisotropy effects. A fourth-order formulation leads to the determination of the appropriate Greens function for the structure. The characteristic equation is formed through the application of the Galerkin method to the equations resulting from the boundary conditions on the strip. Numerical results calculated by this method for isotropic as well as dielectrically anisotropic substrates are compared with the existing data, and in both cases a very good agreement is observed. New data on the propagation constant of the shielded microstrip with different substrate permittivities and permeabilities are presented to illustrate the effects of the material parameters on the characteristics of the microstrip line. >

Frequency-dependent characteristics of shielded broadside coupled microstrip lines on anisotropic substrates

A spectral-domain technique is applied to compute the propagation characteristics of a shielded broadside coupled microstrip line printed on homogeneous uniaxial and biaxial substrates. The formulation derives the Greens functions for even and odd modes of the guiding structure via the transformed fourth-order differential equations. The analysis includes anisotropic substrates which are simultaneously characterized by both ( epsilon ) and ( mu ) tensors. This rigorous full-wave approach to the solution of the problem is shown to yield results agreeing well with the existing data. The propagation characteristics are studied with respect to different line width/thickness ratios as well as to the material substrate parameters. >

Microstrip resonators on anisotropic substrates

The spectral domain method is applied to study shielded microstrip resonators printed on anisotropic substrates. A Greens function that takes into account the dielectric anisotropy effects is derived through a fourth-order formulation. Galerkins method is then applied to form the characteristic equation from which the resonant frequency of the microstrip resonator is numerically obtained. Results for a microstrip situated on an isotropic substrate are used to validate the theory. >

Analysis of bilateral fin-lines on anisotropic substrates

A full-wave analysis of the bilateral fin-line on anisotropic substrates is presented. The supporting medium is characterized simultaneously by both nondiagonal second rank ( epsilon ) and ( mu ) tensors. The dyadic Greens function is formed rigorously in the discrete Fourier transformed domain and is used to study the propagation characteristics of the fin-line. The Greens function elements are given explicitly in their closed forms along with the verification of the theory. New data describing the dispersion properties as functions of the coordinate misalignment are also generated for several substrate materials. >

Effects of misalignment on propagation characteristics of transmission lines printed on anisotropic substrates

The spectral-domain method is applied to study the propagation characteristics of grounded transmission lines on biaxial substrates whose axes are misaligned with those of the line. The three structures under investigation are the grounded slotline, microstrip, and the edge coupled line. In the formulation, an expression for the Greens function that is valid for substrates which are simultaneously characterized by their permittivity and permeability tensors is derived. The off-diagonal elements of the permittivity tensor, present due to the misalignment of the axes, are used to examine the dispersion properties of these transmission lines with numerous case-studies presented for different angles of rotation. >

Anisotropic effects on scattering and radiation properties of two-dimensional objects

Many composite materials that are used in practice exhibit anisotropic properties. To account for these effects, several integral-equation formulations for scattering and radiation by anisotropic objects have been proposed. The authors present some numerical results on how the anisotropy affects the scattering behavior of a thin plate and radiation characteristics of a line source placed inside a cylindrical shell.<<ETX>>