Said Ghnimi

A new design of an S/X dual band circular slot antenna for radar applications

Abstract A novel design of dual-band slot antenna with a circular patch for radar applications is presented and studied. It is fed by a micro-strip line and built on a FR-4 substrate with a whole size of 18 X 30 mm2. A dual band printed antenna is created by introducing slots on the radiating element. By this, two bandwidth, covering C and X band, are achieved. In order to obtain a good fundamental antenna design, the initial studies were carried out theoretically, using CST Microwave Studio simulation software. In this case, the frequency range at return loss <10 dB is 5.24–6.16 GHz for low frequency and is 7.9–11.7 GHz for high frequency. In addition, the proposed antenna has good radiation characteristics and stable gains over the whole operating bands. A prototype of antenna is fabricated and tested. Experimental data show good agreement between simulated and measured results.

Electromagnetic propagation environment effects on the WiMAX communication system

The goal of this paper is to study the electromagnetic environment of WiMAX (worldwide interoperability for microwave access) communication system working at 3.5 GHz. For this, we have analyzed and compared the radio signal loss in urban, suburban and rural environment with different receiver antenna height. The path loss prediction is obtained by three propagation models: SUI (Stanford University Interim), COST Hata and Ericsson model. The analysis was made using MATLAB software. The results shows that in general SUI model predict the lowest path loss, especially in suburban environments.

Indirect influence of lightning EM field induced in a power line on the high frequency transmission line

In this paper the time domain modelling of a transmission line coupling by an external EM fields is described. These fields generated by a nearby lightning stroke induced in an electricity transport and distribution power lines. To model this coupling, we have used the equivalent circuit taking in consideration the different physical concepts based on the theoretical Taylors formulation. The numerical inversion of Laplace transform method is employed to solve the different equations derived from the equivalent circuit models. Results obtained by this model present the response voltages and currents induced in the transmission line used in the mobile telecommunication circuit.

Optimal algorithm for the numerical inversion Laplace transforms method in a multiconductor transmission line system

The current paper presents a study on the numerical method of inversion of Laplace transforms (NILT) to deal with some of EMC problems in MW systems under the Matlab environment. The idea consists in studying the two well used algorithms in NILT, one is called quotient-difference algorithm using expansion of the Fourier series and the other is called epsiv-algorithm using the expansion of Laguerre function, in order to reach an optimal algorithm of the NILT method for different multiconductor transmission line (MTL) systems. The simulation results show that the quotient difference algorithm is most efficient than the epsiv-algorithm in term of rapid convergence to zero with a low relative error; these performances increase significantly the use of Laplace transform inversion by the method of Laguerre in MW circuits.

New Experimental Investigation of Magnetic and Electric Fields in the Vicinity of High-Voltage Power Lines

In this paper, the theoretical and experimental characteristics of magnetic and electric fields in the vicinity of high voltage lines are investigated. To realize these measurements and calculations, we have developed some equations for two overhead power line configurations of 150 ㎸ (single circuit, double circuit), based on Biotsavart law, image and Maxwell theories, in order to calculate the magnetic and electric fields. The measurements were done to a maximum distance from the tower of 50 m, at a height of 1m from the ground. These experiments take into consideration the real situations of the power lines and associated equipment. The experimental results obtained are near to that of the Biot-Savart theoretical results for a far distance from the tower; and for a distance close to the power line, the results from the image theory are in good agreement with the experimental results.

BER perfermance of GMSK modulation under radio mobile propagation environments

This paper treats the BER performance of GMSK modulation under different radio mobile environments. Studies of GSM performances in various radio mobile environments such as in AWGN channel and in multipath fading channel (one path fading and four path fading cases) were performed. A random data was used as an input to the simulation program in the Matlab environment and the output was stored in the form of Bit Error Rate (BER) as a function of signal-to-noise ratio (Eb/No).

Exprimental investigation of the GSM transmission quality in the vicinity of the power line system

In this paper we have analyzed the GSM (Global System for Mobile communications) transmission quality in the vicinity of the power line system and its EM effect to the RF interface of the mobile telecommunication system. These electric lines and its associated equipments produce the noise around their proximity, which are likely to have dangerous effects on their environment. The characteristic of the power line noise and its correlation with the GSM burst; showing that the considered noise source to the mobile station (MS) and Base Transceiver Stations (BTS) of GSM system is due to the presence of fundamentals and harmonics fields (electric and magnetic fields) in the proximity of power lines functioning at the permanent state; specially the present of the 5th harmonic field which is close to the GSM pulsed field at the frequency 217 Hz. The measurements and simulated results of GSM system were done inside and outside an area of 50m distance from the tower of power line. These experiments take on consideration the two real situations (in the case of the presence of BTS and in the case of the absence of the BTS of the GSM equipments). It has been observed that the effect of the power line on the quality of service (QoS) of GSM signal in idle mode and dedicated mode is more important, and the experimental results show the influence leading to a degradation of the reception level (RxLev) and the reception quality of the GSM signal (RxQual) with an important Frame error rate (FER).

Theoretical and simulation of crosstalk between two strip lines using multiconductor transmission line

This paper treats the crosstalk between strip lines using the classical theory of multi-conductor transmission lines (MTL) in a homogeneous medium. The extraction of S parameters theoretically by MTL method and by simulation with advanced design system momentum software (ADS) give almost the same characteristics. Also an investigation has been made on the dependence of the crosstalk according to different values of the substrate dielectric permittivity and the height of the substrate showing that there is an optimum value of these parameters for less crosstalk.

Theoretical and Simulation of Crosstalk Between Two Strip Lines Using Multiconductor Transmission Line

This paper treats the crosstalk between strip lines using the classical theory of multi-conductor transmission lines (MTL) in a homogeneous medium. The extraction of S parameters theoretically by MTL method and by simulation with advanced Design System Momentum software (ADS) give almost the same characteristics. Also an investigation has been made on the dependence of the crosstalk according to different values of the substrate dielectric permittivity and the height of the substrate showing that there is an optimum value of these parameters for less crosstalk.