Ursula C. Resende

Evaluation of Singular Integral Equation in MoM Analysis of Arbitrary Thin Wire Structures

In this paper, a new simple and efficient numerical procedure is presented for evaluating electric field singular integral equations found in the method of moments (MoM) analysis of electromagnetic scattering by arbitrary thin wire structures. The analysis is conducted using triangular basis and weight functions. The singular kernel is modeled as a first-kind elliptical integral and evaluated using the arithmetic geometric mean. Numerical integration is used only when there are no singular kernels. Tests in dipoles, a loop, and a spiral are provided to illustrate the proposed techniques accuracy and computational efficiency.

Yagi-Uda antenna optimization by elipsoid algorithm

This work presents a mono-objective optimization for a Yagi-Uda antenna applying the ellipsoid algorithm. For problems which the objective function is not known, like function that represents the Yagi-Uda antenna behavior, the ellipsoid algorithm has some features that make it more interesting compared to other optimization methods. To obtain antenna electromagnetic characteristics it is used the electric field integral equation (Pocklington integral equation) numerically evaluated by the Method of Moments (MoM). The ellipsoid optimization leads to antenna geometry with superior directivity than those presented in the available literature.

Electromagnetic Scattering Analysis of Arbitrary Structures by the Natural Element Method Coupled With Absorbing Boundary Condition

The problem of determining the electromagnetic scattering of arbitrary structures consisting of both dielectric and conducting materials are analyzed in this paper by the natural-element method coupled with the absorbing boundary condition (NEM-ABC). By this method, the target is first enclosed by a fictitious boundary. Maxwells equations are then solved by NEM inside and ABC is applied on the fictitious boundary. The results are compared with analytical and finite-element method-ABC ones which show the robustness, applicability and relevance of the method.

A Meshless Approach Using EFG Interpolating Moving Least-Squares Method in 2-D Electromagnetic Scattering Analysis

In this paper, the element-free Galerkin method with special interpolating shape functions is used to solve an electromagnetic scattering problem. These shape functions make use of the interpolating moving least-squares method that guarantees the Kronecker delta property. This allows enforcing the absorbing boundary condition directly in the discrete system, consisting of a more practical way when compared with other methods, such as the Lagrange multipliers. The technique is applied to the analysis of electromagnetic scattering generated by an infinite dielectric cylinder illuminated by a TMZ plane wave and a sensibility analysis is done in which the numerical results are compared against the analytical solutions.

Approximated raising of the curvature of a double-ridged waveguide horn antenna in a computational model

In this paper the curvature and the shape of the double ridged horn antennas is studied in its computational modeling, whose application is very significant for EMC/EMI tests. The ridges, curved structures inside the double ridged horn antennas, are an important structural parameter. Its curvature is described by a function, and this function needs a mathematical treatment when building its 3D geometry in a computational model. When the function of the ridges is not known, an approximated function is an available approach to build its 3D structure. To accurately characterize the double ridged horn, an approximated function of the ridges is raised and implemented in a computer simulation. The approach was verified and results show significantly consistency with manufacturers data.

Analysis of omnidirectional dual-reflector antennas with radomes

We investigate the influence of dielectric radomes on the electromagnetic performance of dual-reflector antennas suited for omnidirectional coverages. The dual-reflector systems are fed by a TEM coaxial horn. Accurate analyses are provided by surface integral equations numerically evaluated by the method of moments, taking into account all electromagnetic couplings among the several antenna elements. The analyses demonstrate that lambda/2-window radomes do not significantly influence the antenna behavior across the operation band. But the way the radome is attached to the dual-reflector structure may significantly influence the sidelobe levels of the radiation pattern.

Conformity evaluation of radiated immunity standards to modern telecommunication services using statistical techniques

Telecommunication services have faced significant improvements along the last decades, mainly related to new modulation techniques. Consequently, signals waveforms have gradually been modified. In this scenario, Electromagnetic Compatibility and, specially, Radiated Immunity tests became necessary to ensure the performance of electronic devices when exposed to such signals. Considering that the waveforms and modulations specified in Radiated Immunity standards are much simpler than those currently used in Telecommunication services, a statistical study about the impact of this difference is proposed for the 210–216 MHz frequency range.

Evaluation of Electromagnetic Scattering by Conducting Bodies of Revolution With Discontinuous Currents

In this paper, the electromagnetic scattering by conducting bodies of revolution with discontinuities in the equivalent surface currents is investigated. The simulations are based on the combined field integral equation evaluated by the method of moments. A strategy for implementing an integral equation formulation with appropriate testing functions is presented. The procedure is applied in the analysis of the TE11 mode propagation inside a circular waveguide and the radiation from a circular corrugated horn antenna. The effectiveness of the proposed method is illustrated by comparing numerical results with analytical and experimental data.

Signal Integrity Considerations Applied to Automotive Grounding System's Design

Designing electric circuits which have the vehicles body as a part of the currents path is a common practice in the automotive industry. In this case, the signal integrity is affected by many variables, e.g. the bodys shape and its constituent materials. Nevertheless, the design of the vehicles body is generally based only on esthetic and aerodynamic factors and signal integrity is not taken into account. This is not a great concern anyway, since this kind of signal usually comes from power supply and the electrical and electronic devices might work (at least partially) even with a voltage level decrease. However, although power supply signals are theoretically continuous, higher frequency components can be noticed through measurements. Besides that, the implementation of Power Line Communication system in vehicles is being studied lately, which means that the traditional power lines would also carry information signals, with associated high frequency content. These observations lead to a concern about the bodys behavior when conducting higher frequency currents, since it is not considered for the design of the vehicles grounding systems. In this case, it is desirable that these spurious frequency components have a minimum impedance path to the batterys negative pole. This goal can be achieved by calculating optimal points for the grounding points. However, this is not an easy task, since there are no analytical equations for the impedance in this case. Hence, this paper proposes the use of the Genetic Algorithm as a tool for numerically calculating the best grounding points in a vehicle, through the electromagnetic simulation software ANSYS HFSS®.

Wireless power transmission and reception system using UWB CPW-Fed Microstrip antenna

This brief describes a wireless power transmission and reception system using UWB CPW-Fed Microstrip antennas and discrete components. A square wave oscillator is used as an excitation source to a Gaussian pulse generator. This pulse is then shaped and differentiated by an RC for posterior transmission. The pulse is transmitted with a 50-cm greater distance with an 8 ns width and is semi-rectified in the reception and applied in a resistance.