M. R. M. L. Albuquerque

Effect of the Dielectric Anisotropy on the Propagation Properties of Microstrip Tapers with Height Variations

This paper deals with the design and application of nonuniform microstrip transmission lines on anisotropic substrates. A rigorous analysis is based on the use of Hertz vector potentials, moment method and transmission line theory to determine the dispersion characteristics of single and coupled tapered microstrip lines for accurate performance prediction. Results are presented for the main parameters providing the necessary information to design several devices on tapered microstrip, with variation on the strip width and dielectric height, for (M)MIC and antennas applications. A good agreement was observed with the results available in the literature for tapered lines on isotropic substrates.

Spectral domain analysis of coupled microstrip lines on magnetized ferrite substrates

Dispersion characteristics of coupled microstrip lines on ferrimagnetic substrates are presented and their features discussed. The Hertz vector potentials in the spectral domain method are used to calculate the dyadic Greens functions in an impedance matrix form. The behavior of the propagation constants is obtained by using the spectral Galerkins technique. Numerical results are found as a function of various geometrical parameters and of the externally applied static magnetic field. Nonreciprocal behavior is mainly observed when the static magnetic field is applied in the transverse direction, parallel to the ground plane.

Analysis and design of fractal-like circular patch elements for miniaturized and stable FSSs

An analysis of a fractal-like circular patch element for miniaturized frequency selective surfaces (FSSs) is presented. The analysis is performed using the Wave Concept Iterative Procedure (WCIP), a full-wave method. The proposed FSS geometry has a stable frequency response in relation to the oblique incidence of plane waves. In addition, the FSS patch element presents a fractal-like behavior, being suitable for miniaturization. Simulation results using WCIP are compared with simulations carried out through HFSS software to validate the model. The proposed model accuracy is also verified by means of comparisons between simulations and experimental results.

Ferrite substrate in patch antennas for millimeter wave applications

This paper aims to study the radiation characteristics of annular ring microstrip antennas printed on a double-layered substrate that is constituted by an isotropic and a ferrite layers. The influence of the applied dc magnetic bias field on the radiation characteristics of these structures is examined. The analysis is performed in the Hankel transform domain using Hertz vector potentials and Galerkin method. Numerical results are presented for the antenna main characteristics such as resonant frequency and radiation pattern.

Tapered microstrip line circuits on anisotropic substrates with height variations

The analysis of tapered microstrip lines on anisotropic layers with height variations is performed by using a combination of Greens function, the moment method and transmission line theory. The characteristic impedance and the phase constant along the microstrip tapered line are obtained, allowing the determination of the input parameters of microwave integrated circuits, such as microstrip tapers with linear, exponential, parabolic and cosine-squared variations on the strip width.

Accurate Analysis of Microstrip Lines on Lossy Biaxial Anisotropic Substrates

We have studied the behavior of the microstrip lines on lossy biaxial anisotropic dielectric substrates. A spectral-domain moment method is used with the Galerkin testing procedure to determine the dispersion characteristics of single and coupled lines. Modes of both even and odd symmetries are included. It is found that the anisotropy of the substrate has a significant influence on the propagation characteristics. The theory is verified by comparison with previously published data.