Mohamed Essaaidi

Compact Disc Monopole Antennas for Current and Future Ultrawideband (UWB) Applications

Circular disc monopole antennas are investigated for current and future ultrawideband (UWB) applications. The studied antennas are compact and of small size (25 mm × 35 mm × 0.83 mm) with a 50-Ω feed line and offer a very simple geometry suitable for low cost fabrication and straightforward printed circuit board integration. More specifically, the impedance matching of the classic printed circular disc UWB monopole is improved by introducing transitions between the microstrip feed line and the printed disc. Two particular designs are examined using a dual and single microstrip transition. By using this simple antenna matching technique, respective impedance bandwidths (|Sn | <; -10 dB) from 2.5 to 11.7 GHz and 3.5 to 31.9 GHz are obtained. Results are also compared to a classic UWB monopole with no such matching network transitions. Measured and simulated reflection coefficient curves are provided along with beam patterns, gain and group delay values as a function of frequency. The transient behavior of the studied antennas is also examined in the time domain.

Planar circular disc monopole antennas using compact impedance matching networks for ultra-wideband (UWB) applications

Two planar circular disc antennas that utilize compact impedance matching networks for current and future ultra-wideband (UWB) applications are investigated. The proposed designs have a physically small size (30 mm × 35 mm) and simple geometry, and offer a relatively large bandwidth (BW). Input energy is launched through a 50-Ω feedline (attached to a K-Connector) and broadband antenna matching is improved by introducing transitions between the feedline and the printed circular discs. Specifically, two designs are investigated using single- and duel-microstrip line transitions. By using this antenna matching technique, respective BWs (|S11|≪−10 dB) of 3.18 to 11.74 GHz and 3.47 to 31.94 GHz are obtained. Results are compared to an analogous UWB monopole with no matching network transitions. Measured and simulated radiation patterns are presented along with reflection loss values up to 40 GHz.

An efficient algorithm for the global modeling of RF and microwave circuits using a reduced nonlinear lumped network (RNL/sup 2/N)-FDTD approach

In this letter, we present an efficient and simple reduced nonlinear lumped network (RNL/sup 2/N)-FDTD method for the global modeling of RF and microwave circuits. This method is a simplified version of the original nonlinear lumped network (NL/sup 2/N)-FDTD approach, which does not require a complicated precalculation and a huge back-storage compared to the former version.

Wireless Sensor Network applications in smart grid

The decentralized and lightweight architecture of Wireless Sensor Networks (WSNs) have made them ubiquitous in several scientific, medical, military, and recently in smart grid applications. They enabled pervasive computing and the implementation of intelligent systems. Recently, they have been used in todays electric power systems, to bring about intelligence and implement some of the smart grid function in generation, delivery, distribution, and customers. They are becoming a vital component of the smart grid. Their advantages come with challenges because of harsh environment and stringent quality of service requirements. This paper describes different components of smart grid and then provides an overview of WSNs application in different part of smart grid and presents their opportunities and challenges for future work in diverse areas of smart-grid applications. The paper shows an example implementation of building monitoring system.

A novel compact multiband planar antenna for wireless and mobile handsets

In this paper, a novel printed compact multiband planar antenna is proposed for wireless and mobile handsets. The radiating patch of this antenna is designed jointly with the shape of the ground plane. This antenna covers the 3G Universal Mobile Telecommunication System (UMTS; 1920–2170 MHz), Bluetooth (2400–2484 MHz), Wi-Fi (2400–2484, 4900–5000, 5150–5250, 5150–5350, 5470–5725 MHz] and Worldwide Interoperability for Microwave Access [Wimax; [(2400–2600), (3400–3600)] MHz]. The features of each band can be easily optimized by tuning the position, shape, and size of the embedded slots in the radiating patch, and the height of substrate. This antenna performances were optimized using CST simulator and were validated using Ansoft HFSS.

Conserving energy in WSN through clustering and power control

Wireless Sensor Networks raise a growing interest among industries and civil organizations where monitoring and recognition of physical phenomena are a priority. Their possible applications are extremely versatile and are expected to be intensely applied in different domains such health, agriculture, habitat monitoring, routing traffic, security and military. WSN represent a significant technology that attracts more and more considerable research attention in recent years. It has emerged as a result of recent advances in low-power digital and analog circuitry, low-power RF design and sensor technology. Wireless Sensor Networks consist of a large number of miniature devices called sensor nodes scattered over a geographical area called sensor field. These nodes are attempted to collect information or data which is forwarded through gateways called base stations. The communication scenario through sensor nodes leads to some amount of energy wasting. Therefore we need to design suitable techniques and protocols in order to optimize the energy consumption and increase the network lifetime. This paper proposes a novel energy-aware framework for a long-lived sensor network. Our framework is based on clustering architecture and achieves a good performance in terms of lifetime by minimizing energy consumption for in-network communications and balancing the energy load among all the nodes. In fact, its an energy optimization approach based on cross-layer for wireless sensor networks, joining optimal design of the physical, medium access control, and routing layer. The framework enables the network to be dynamically reconfigured and efficiently using every nodes energy and distributes management tasks to support the scalability of the management system in densely deployed sensor networks. This approach focuses on the computation of optimal transmission power, routing, and duty-cycle schedule that optimize the WSNs energy-efficiency and by the way, reduces node energy consumption and contributes to extending the lifetime of the entire network. The approach is evaluated using the NS2 simulator. Simulation results show that it is an energy-efficient approach and able to achieve significant performance improvement as well.

A compact T-shaped antenna for dual-band WLAN communications

In this paper, a new design of a compact T shaped microstrip antenna for multioperating bands of wireless communication systems is presented. The proposed antenna has the multiband measured performances covering 2.4 GHz band WLAN (2.4–2.484GHz), and the 5-GHz band WLAN (5.15–5.35/5.725–5.825 GHz). Several properties of the proposed compact antenna for multiband operation such as impedance bandwidth, radiation pattern, and measured gain have been numerically and experimentally investigated.

Fast convergence mechanisms and features deployment within operator backbone infrastructures

The goal of backbone operators like: Orange/France telecom, Cegetel , AT&T, Sprint, BT…etc, is minimizing impact on customer applications due to failures and interruptions within their backbone. Data backbones based on MPLS /VPN infrastructures are widely deployed over the world, giving connectivity to enterprises and public users with on demand added services. Ideally: customers will see no interruption at all, tending to make backbone failures as transparent as possible to end applications. That is why tuning configuration of routers and routing mechanisms, introducing features that help to minimize interruption durations within the backbone. In this paper we will give an overview of fast convergence mechanisms and features deployment within data network infrastructures. Will be discussed standard features like: “bidirectional failure detection” (BFD) [1] which provides fast failure detection for all media types, encapsulations, topologies, and routing protocols, and how it is the way to go when the physical media does not provide any way of detecting a failure, fast enough to meet fast convergence design requirement, Mpls ldp-igp synchronization [5]: which ensures that LDP is fully established before the IGP path is used for switching. It achieves this by not building IGP neighbor-ship before the LDP [6] neighbor-ship is established, will be discussed also some other relevant features ….

Global Modeling of Microwave Three Terminal Active Devices Using the FDTD Method

Abstract : This paper presents a new approach for the global electromagnetic analysis of the three-Terminal active linear and nonlinear microwave circuits using the Finite-Difference Time Domain (FDTD) Method. Here, we have updated the both electric field components on the three - terminal active device by correlating the voltage and current with its impedance. This approach is applied to the analysis of a linear amplifier which includes a three-terminal active MESFET device. Simulations results are in good agreement with those of the commercial tool.

An overview of smart grid cyber-security state of the art study

Smart Grid is the most outstanding engineering achievement of the 21st century in power systems. This is an emerging technology that is revolutionizing the conventional electric grid by providing new services based mainly on information Communication technology (ICT), which is considered to be its main enabler. Besides the different opportunities and advantages offered by ICT, Smart Grid suffers from its inherent challenges, especially, at the level of cyber-security. Consequently, there are several security threats that may affect Smart Grid. These can be divided into three categories, namely, people and policy threats, platform threats and network threats. To address these threats several approaches and mechanisms were developed based on cryptographic methods, authentication protocols and firewalls. This paper is dedicated to an overview study on Smart Grid Cyber-security challenges and to the different approaches available to address the different security threats.