Patrick Vaudon

Interference Supression of the Linear Antenna Arrays Controlled by Phase with Use of Sqp Algorithm

The performance of mobile cellular radio networks is limited by the level of cochannel interference that can be tolerated. The use of antennas arrays is very helpful in enhancing the performance and capacity of the wireless communication system. This paper presents a method for antenna pattern synthesis that suppress multiple interfering narrow or wide band signals while receiving the desired signal by controlling only the phase. Excitation phases are computed using the Sequential Quadratic Programming (SQP) technique. This method transforms the nonlinear minimization (or maximization) problem to a sequence of quadratic subproblems, based on a quadratic approximation of the Lagrangian function. 252 Mouhamadou et al.

Application of fractional derivatives to the FDTD modeling of pulse propagation in a Cole–Cole dispersive medium

This article presents an application of the fractional derivative concept to the modeling of the time-domain propagation in dispersive Cole-Cole media. A recursive finite-difference(SINGLEBOND)time-time-domain (FDTD) formulation is developed to solve the special differential equation that is obtained. This formulation is validated by comparing the calculated permittivities to analytical values.

Influence of the ground plane structure on the radiation pattern of microstrip antennas

Most radiation analyses of microstrip antenna are based on the assumption of an infinite ground plane. Actual environments are different, and the ground plane is necessarily limited. In this paper, we show the influence of the dimensions and the shape of the support. Analytical formulations are explicitly given. Many comparisons between theory and experimentation are presented. Next, we apply the previous results to the case of a circularly polarized antenna, in order to optimize the ellipticity ratio.RésuméLa plupart des methodes ďanalyses du rayonnement des antennes supposent que le plan de masse sur lequel elles reposent est infini. Ces études, purement théoriques, ne correspondent pas à lew implantation pratique. On se propose de montrer quelle est ľinfluence des dimensions et de la forme du support sur le diagramme de rayonnement. Les formules analytiques permettant de calculer cette influence sont explicitement données dans le cas ď un support plan limité, ď un support polygonal et cylindrique. Plusieurs exemples de comparaisons théorie-expérimentation sont présentés. Enfin, nous montrons comment ďeffet du support peut être exploité dans le cas des antennes à polarisation circulaire, afin ď optimiser lews performances.

A Smart Antenna Simulation for (DOA) Estimation Using MUSIC and ESPRIT Algorithms

In this paper we propose an approach to design a smart antenna system that uses six-port reflectometer. This is done to detect the DOA arrival angles of five incoming RF signals using MUSIC and ESPRIT algorithms. The characteristic of each algorithm are critical in the DOA precisions. The results are deduced from the simulation of the characteristics of the system, using the advanced design system (ADS) and MATLAB

Simulation of Smart Antenna System using ADS Co-Simulate with Matlab: Direction of Arrival estimation and Interference Canceller

In this paper, we present the computer simulation for adaptive antenna system to improve the signal-to-interference ratio by steering beam pattern to track the user signal while maintaining placing the null in the direction of interference signal by updating the weight coefficients using SQP algorithm. In Advanced Design System (ADS), the signal processing co-simulates with either circuit envelope or transient simulators. Antenna and propagation models simulate the effects of radio channel, including signal fading and path loss

Performance measurements of Modified LINC transmitter for wireless applications

The LINC (Linear amplification with Nonlinear Components) transmitter efficiency is not degraded only by the power combiner, but also by the SCS (Signal Component Separator) architecture. In this article, we propose a Predistorted Modified SCS (PM-SCS) architecture and we present the measurement platform dedicated to the LINC system study. Measurement results show an efficiency improvement from 39.60% for regular LINC to 63.80% for PM-LINC.

A general formulation for asymptotic expansions with a pole near the saddle point

We describe the two uniform asymptotic expansions which already exist and which are commonly used in asymptotic electromagnetic theories, when a pole approaches the saddle point. Then, we establish a simple relation between these two expansions. By analyzing this relation, we give the general form of any asymptotic expansion with a pole near the saddle point. By using diffraction integrals, we give explicit examples and compare the corresponding numerical computations. Then we conclude by examining the specific problem of many coalescing poles singularities.RésuméCet article reprend les deux principales études concernant les développements asymptotiques uniformes lorsqu’un pôle se trouve prés du point de selle et établit une relation simple entre le développement de Pauli Clemmow et le développement de Van der Waerden. Ľ analyse de cette relation permet de proposer une forme plus générale pour des développements asymptotiques. A partir ďexemples explicites (au premier ordre), des comparisons numériques avec les solutions exactes sont réalisées. Enfin, le cas spécifique plus complexe des développements asymptotiques susceptibles de présenter plusieurs pôles prés du point de selle est examiné.

A novel low SAR water-based mobile handset antenna

This paper suggests a novel water-based cellular phone antenna construction for reducing the electromagnetic wave radiation coming from mobile antenna toward human head. The antenna is based on a PIFA structure operating at 1.8 GHz. The Specific Absorption Rate (SAR) is decreased by reducing the current density on the human head. The reduction of SAR is carried out by introducing a U-edge made of an absorbing water material at each corner of the ground plane.

A wave propagation model based on Monte-Carlo particle-tracing

This article describes a new wave propagation model based on Monte-Carlo particle-tracing. This model relies on Monte-Carlo integration and Huygens currents radiating. The particles used to compute the field permit to consider the interferences. This model includes the diffraction of the surface without edge computation. The implementation of this propagation model is based on a image synthesis renderer.We study the results of this model in far field situation with perfectly conducting shapes, by comparing results with a classical MoM Method.

Complex weight control of array pattern nulling: Research Articles

The new generation of System-on-Chip (SoC) incorporates digital, analogue, RF/microwave and mixed-signal components. Such circuits impose to reconsider the traditional design methods. Mixed-signal designers need novel design methodologies which will have to include accurate behavioral libraries of devices and processes into hierarchical design flows. Thus, this paper describes a behavioral modeling approach which generates neuro-fuzzy-based models for RF/microwave devices. The models, so obtained, can be easily integrated into a VHDL-AMS simulator. This modeling approach is applied to a microwave tunable phase shifter and it is illustrated by the development of a VHDL-AMS model library for RF/microwave applications.