Walter G. Fano

Simulación numérica de la permeabilidad magnética aplicada a ferritas utilizando algoritmos genéticos

The magnetic permeability of a ferrite is an important factor in designing devices such as inductors, transformers, and microwave absorbing materials among others. Due to this, it is advisable to study the magnetic permeability of a ferrite as a function of frequency. In this paper, ferrites were considered linear, homogeneous, and isotropic materials. A magnetic permeability model was applied to NiZn ferrites doped with Yttrium. The parameters of the model were adjusted using the Genetic Algorithm. In the computer science field of artificial intelligence, Genetic Algorithms and Machine Learning does rely upon natures bounty for both inspiration natures and mechanisms. Genetic Algorithms are probabilistic search procedures which generate solutions to optimization problems using techniques inspired by natural evolution, such as inheritance, mutation, selection, and crossover. Genetic Algorithm is most successful in finding the global minimum solution regardless of the initial values versus the method of nonlinear least squares usually used to adjust parameters.

Near field magnetic probe applied to switching power supply

Near field measurements are a useful tool in the design process of a PCB board. It is a fast method to find which part of the circuit generates electromagnetic emissions and check if the solutions proposed actually works. This paper shows the construction of a Near Field Magnetic Probe, its characterization, and the explanation that how the correction factor can be obtained and measured as a function of the frequency. The Near field magnetic probe is basically a short loop antenna with a magnetic core to increase the sensibility, at the frequencies of switching power supply of a the Personal Computer. The construction of this probe is the first step for the construction of an automatized measurement system.

Microstrip antenna design using EBG (Electromagnetic Band Gap) structures at 2.4GHz

The objective of this work is the application of EBG structures (metamaterials), working at frequency of 2.4 GHz to improve the behaviour of the patch antenna widely used in communications. It is explained how the dimensions of the design are obtained to achieve the objectives, and how the radiating element with the metamaterial works together. The distance between the patch and metamaterial to improve several parameters simultaneously: antenna impedance, SWR, Reflection Coefficient, Gain, Radiation Pattern, have been a contribution of this work, because this distance is not in the bibliography. An isolated patch, and two patches with metamaterials were constructed to study the behavior between the metamaterial and the patch antenna. Construction was performed with commercially used FR4 material, showing that working properly at the frequency f = 2.4 GHz.

Overhead Quasi-Coaxial Transmission Lines

Design expressions for overhead quasi-coaxial transmission lines are developed and presented in a simplified form, suitable for engineering purposes. The electrostatic logarithmic potential method is used for low-, medium-, and high-frequency applications, where the line dimensions in wavelengths are quite low, so it is not necessary to take into account the retarded potential. This kind of transmission line is very useful and convenient for high-power broadcast transmissions, due to the high power capacity and very low attenuation of the line. This is especially important when the distance between the transmitting building and the radiating system is quite large.

Eficiencia de blindaje de nuevos materiales

In this paper the shielding efficiency of an artificial material formed of a periodic structure defined by a unit cell composed of bronze cylinders located between two dielectric planes has been studied.

Metamaterial's effective electric permittivity model

In this paper we study an artificial material composed of a periodic structure defined by a unit cell containing cylindrical electrical conductors. These materials, called metamaterials, have special electromagnetic properties such as simultaneously negative magnetic permeability and electrical permittivity, which could not be obtained from homogeneous materials that exist in nature. An analytical model for effective electrical permittivity of the entire system in terms of the dimensions of the unit cell and frequency is obtained. We also study how to vary the resonance frequency of the artificial material in which the effective permittivity is negative. This analysis enables the fabrication of structures whose properties can be modified to be applied in shieldings. Kramers Kronig relations, suited for verifying causality in electrical permittivity models by relating the real and the imaginary parts of the dielectric permittivity is also studied. The imaginary part of the effective permittivity has been obtained numerically by applying the Hilbert transform to the real part of the permittivity simulated by the proposed Model thus verifying the Kramers-Kronig relations.

Slanted Wire Fed Grounded Monopole Characteristics

The slanted wire grounded monopole is a very simple system. Its fed from a wire skirt, exhibits a resistive impedance and the inductive reactance can be nullified with a variable capacitor. Since the physical antenna behavior is not always clearly explained, to show the vertical radiation characteristics of the antenna height versus the antenna radius, as it is modified by the slanted wire, we present this paper. The high angle radiation is larger compared to the standard cylindrical series fed monopole of the same height, and for this reason in the U.S. the F.C.C. prohibited this system to be used at night. This paper determines the actual antenna characteristic according to the tower height and effective radius using the moment method software code. If one sets the antenna height to be used with similar radiation pattern as the traditional cylindrical series fed monopole this radiating system presents a very low area to ice accumulations and allows placing lightning beacon and other R.F. radiating systems with no technical problems.

Emisiones electromagnéticas de una computadora personal (PC) con monitores de cristal Líquido y tubo de rayos catódicos

This work is devoted to the measurements of the electromagnetic radiation of a personal computer, first connected to a LCD monitor, and then to a monitor CRT.

Conference on Electromagnetic Compatibility (EMC), Antennas and Propagation

In October 2013, the Conference on Electromagnetic Compatibility, Antennas and Propagation, was held at the Faculty of Engineering of the University of Buenos Aires (FIUBA), in the Hall of the Board. The conference was organized by the IEEE EMC and AP Joint Chapter of Argentina, the Faculty of Engineering at the University of Buenos Aires and the National Institute of Industrial Technology (INTI).