Jean-Marie Floc'H

Study of an Electrochemically-Deposited 3-D Random Fractal Tree-Monopole Antenna

A 3-D fractal-tree monopole antenna was realized using electrochemical deposition technique. Experimental results on the return loss over the band 1-20 GHz and radiation patterns at all resonating frequencies were presented. The multiband electromagnetic behavior of the antenna was studied and compared to a previously reported 2-D fractal-tree antenna studied by C. Puente It is shown that the impedance bandwidth of the 3-D structure were improved compared to the reported 2-D structure with less dense band distribution. The resonating bands of the fractal structure are related to the length distribution over the fractal shape. Results for the 3-D fractal-tree antenna structure show the expected self-similar behavior

Design of printed dipole with reflector and multi directors

In this paper we present the design of a printed dipole antenna by gradually adding directors in order to increase the gain (like Yagi Antenna). The first design has been presented in publication [1]. This kind of antenna is well known in IETR laboratory [2] and can be used in many applications and frequency bands. It is also well suitable for broadband and multi bands applications [3, 4 and 5]. We have focused this study around the 3 GHz WLAN band. The goal of this study is to determine the best configuration for optimised performances with single antenna or antenna array.

Antenna Directivity Measurement in Reverberation Chamber From Rician

Reverberation chambers are well known for providing a random-like electric field distribution. Detection of directivity or gain thereof requires an adequate procedure and smart post-processing. In this communication, a new method is proposed for estimating the directivity of radiating devices in a reverberation chamber (RC). The method is based on the Rician K-factor whose estimation in an RC benefits from recent improvements. Directivity estimation relies on the accurate determination of the K-factor with respect to a reference antenna. Good agreement is reported with measurements carried out in near-field anechoic chamber (AC) and using a near-field to far-field transformation.

K

An integral equation formulation for the analysis of the electromagnetically coupled microstrip dipole, is briefly described. Typical results for the resonant frequency, the self-impedance and the radiation patterns are compared to experimental measurements in X band. The line parasitic radiation, which was previously assumed to be negligeable, is clearly shown, and its effect is computed.

-Factor Estimation

Sets of design equations for standing wave arrays with transverse electromagnetically coupled dipoles are presented. They are based 1) on the ELLIOTT-STERN design procedure of arrays greatly alleviated when the mutual coupling between radiating elements is neglected and 2) on computed data banks on a single electromagnetically coupled transverse dipole. Practical design of both uniform and non uniform arrays, operating at X band, illustrate the developed methodology.

Self Impedance and Radiation Patterns of the Electromagnetically Coupled Microstrip Dipole

In this work, a novel design of compact dual-band antenna based on the use of split ring resonator (SRR) is presented. The first resonant frequency can be attributed to the excitation of the second microstrip line which acts a monopole antenna; however the second frequency resonance is originated from the excitation of the SRR resonator embedded on the top layer. Excitation of the SRR element is performed by adequately position the microstrip line with respect to the confinement plane of the split ring resonator. The simulated results are analyzed and compared with measured data.

Standing Wave Array of EMC Transverse Dipole Arrays

In a recent publication, authors showed that measurements of the maximum directivity of antennas were achievable in a reverberation chamber through extraction of the coherent part of the field. In this communication, we extend the method to the measurement of the radiation pattern within the main lobe of radiation. One is thus able to estimate the 3dB aperture of the antenna without need of an anechoic chamber. Some preliminary results are reported and possible improvements are discussed.

A dual-band compact antenna with SRR for wireless communication systems

Durante a fase de planejamento da construcao de um novo modelo de hipermercado, um estudo semiotico foi conduzido a partir do discurso dos consumidores consultados nas suas imediacoes, a fim de obter informacoes uteis a realizacao de um arranjo espacial estrategico de suas secoes. Este artigo demonstra como a identificacao de diferentes tipos de valores, atribuidos pelos consumidores a esse ponto comercial, foi usada para ajudar a estabelecer zonas e definir a sua arquitetura interior. O estudo semiotico empregou a abordagem da teoria da significacao desenvolvida por Greimas junto ao Grupo de Pesquisas Semio-Linguisticas.

Radiation pattern measurements in reverberation chamber based on estimation of coherent and diffuse electromagnetic fields

In this paper dual band printed antenna using parasitic elements is proposed for wireless services. The objective of this special design is to compensate the space attenuation difference between the frequency of 2.45GHz and the frequency of 5.8 GHz. Like the space attenuation difference is about 3.5 dB, the studied antenna must to have 3 dB more gain at 5.8 GHz than at 2.4 GHz.

A contribuição da semiótica estrutural para o design de um hipermercado

This paper presents a high-gain antenna for non-contact measurement systems around the frequency ~26GHz. The proposed antenna consists of a slot antenna on a metallic grooved structure with a single frequency selective surface. A small size and improved gain performance are the key objectives of this design. To achieve these two objectives, we use an optimization procedure based on a global algorithm. Both simulation and optimization are carried out by means of a full-wave electromagnetic simulation tool. Afterward, a prototype of the proposed antenna has been manufactured in order to verify their performances. More than 15dB of gain is obtained over the operating frequency range, with approximately 17dB at the frequency 25.5GHz. the small size and high-gain characteristics make this antenna very suitable for non-contact measurement, especially for short-range radar sensors.