Sandro Trindade Mordente Gonçalves

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.

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.

The development of low-complexity ultra wideband circuit transmitter-receiver architecture for digital data transmission using discrete components

The architecture of a low-complexity ultra wideband (UWB) impulse radio (IR) transmitter and receiver circuit, aimed for low-cost applications is presented. To project a simple and commercially available circuit, low-cost discrete components were used in the design. This work presents the circuit schematics, simulations and experimental tests of a transmitter- receiver pair using a microstrip definer CPW fed UWB antenna integrated. The circuit technology used was the Bipolar Junction Transistor, which is widely known and studied and commercially available. The most relevant in this paper was to validate the design of a UWB transmitter-receiver system in a frequency range defined for short distances, more specifically between 3 and 5 GHz at a distance of 10 cm.

Analysis of stability, efficiency and accuracy in the solution of matrix systems in electromagnetic cavity using the FDTD-ADI/LOD method

The finite difference time domain method (FDTD) is widely used in solutions of electromagnetic problems, but has as a condition of stability, the Courant-Friedrich-Levy (CFL), that limits the step time to be used. The method has a high computational processing time and memory usage in three-dimensional analysis for electromagnetic cavities due to the high number of resonance frequencies to be simulated, which makes the analysis complicated and time-consuming. This work presents the stability and efficiency analysis of numerical methods involving electromagnetic cavities using alternating implicit direction (FDTD-ADI) and local one-dimensional (FDTD-LOD) that do not restrict the CFL condition. The electric field values of the FDTD-ADI/LOD methods are obtained through the matrix solution, the numerical method used to solve this system is very important because it affects the stability, precision and efficiency of the results. The numerical methods used in this work will be Thomas, Cholesky and Gauss Seidel.

Sierpinski carpet fractal microstrip arrays for energy harvesting applications

In this work we introduce two fractal microstrip antenna arrays to be used in energy harvesting applications. These arrays were optimized in order to get impedance matching, reduced return losses, high gain and bandwidth. Then, energy harvesting simulations were performed using CST® and the efficiency results for both antennas are presented and discussed.

Improving the geometry of a microstrip antenna for UWB signals through FDTD-CPML method and construction with fiberglass FR4

The Ultra Wideband (UWB) technology is a promising way to integrate data communications over short distances and at higher data rates. It is known that the design of the antenna is critical in the development of UWB systems. This paper proposes a new geometry for a microstrip UWB antenna. The antenna is analyzed using the Finite Difference Time Domain (FDTD) method, simulations using commercial software and experimental results. The analysis will be done by comparing the return loss simulated and measured of the antenna. The proposed antenna is constructed on a plate of FR4 fiber glass.

Evaluation of electromagnetic field emitted by cellular radio base antennae in human head using the Method of Moments

This work studies the electric and magnetic field and specific absorption rate within the human head due to radiation emitted by cellular radio base stations antennae. The Method of Moments is used for numerical evaluation of electric and magnetic field integral equations associated with electromagnetic scattering by bodies of revolution. The representation of the human head is performed using a layered model consisting of five homogeneous layers. The analyses were performed using 850 and 1800 MHz. The results obtained are compared with the limits established by Brazilian standards.

Evaluation of singular integral equation in MoM solution of electromagnetic scattering by bodies of revolution using elliptic integrals

This work presents a technique to evaluate singular integrals present in the solution of electromagnetic scattering by bodies of revolution using Methods of Moments. In this technique, the singular part of the kernels is reduced to an elliptic integral and is calculated in closer form or replaced by an accuracy approximation based in Arithmetic Geometric Mean. The precision and computational requirement of the solution are demonstrated from analysis of plane-wave scattering by perfect electric conductor and dielectric spheres, using CFIE and Müller formulations, respectively.