Design and Measurements of a Quasi-isotropic UWB Planar Antenna

ISSN 1874-4761This paper summarizes the design and measurements of a quasi-isotropic printed UWB antenna, with the analysis of its performances through defined figures of merit. State of the art and review of some recent patents give us the opportunity to exploit some empirical considerations about the shape and the methodology of conception. A simple structure is simulated by means of CST Microwave Studio to show the possibility of fulfilling, at a defined level, UWB antenna requirements such as matching, fidelity and quasi-isotropy of the radiation pattern with a simple micro-strip design and a standard technology. The design of this antenna is based on considerations about bulbous and bended traveling wave antennas. Results of its characterization in anechoic chamber are quantified in terms of amplitude and phase variation, in order to illustrate the level of dispersion for the different directions. The article presents some promising patents on quasi-isotropic UWB antenna

Envelope Factorization with Partial Elimination and Recombination, EF-PER, a New Linear RF Architecture

In this paper, a new architecture for efficient linear radio frequency transmitters is proposed; it includes envelope-tracking (ET) and envelope-elimination-and-restoration (EER) architectures as special instances. The proposed technique is referred to as Envelope Factorization with Partial Elimination and Recombination (EF-PER). It relies on a decomposition of the RF signal before power amplification as a product of two signals, one of them being the envelope signal elevated to an exponent “α”. Compared to ET or EER architectures, the parameter “α” constitutes a new degree of freedom. This allows one to realize good tradeoffs between different performance criteria such as spectrum use, power efficiency, and transmitter linearity. An intuitive aggregate cost function is introduced to capture the desired tradeoff and turns out to be maximized in α=0.5. The full relevance of EF-PER is sustained both by analytical results and realistic simulations performed for OFDM signals. The EF-PER architecture (with α=0.5) has been simulated under Agilent-ADS with a non-linear transistor model from Avago (E-PHEMT) and compared with ET and EER

Safety Critical Systems Analysis

Abstract - A brief overview of the fields that must be considered when designing, implementing safety-critical systems is presented. The notion of safety is most likely to come to mind when we drive a car, fly on an airliner, or take an elevator ride. In each case, we are concerned with the threat of a mishap, which defined as an unplanned event or series of events that result in death, injury, occupational illness, damage to or loss of equipment or property or damage to the environment

The Traditional Indian Ocean Diet

Dietary advice forms the cornerstone in the management of cardiometabolic disease. Though various national and international guidelines suggest different macronutrient proportions, locally framed person-centric diet prescriptions are likely to have a better compliance. In this article, we propose an indigenous traditional Indian Ocean (TRIO) diet, which constitutes a similar pattern of the dietary practices followed by inhabitants of the Indian Ocean littoral region. The TRIO diet highlights on concepts of procurement, preparation, presentation, prioritization, preservation and partaking and may be a good alternative to the Mediterranean diet followed in western countries

Radio-Communications Architectures

Wireless communications, i.e. radio-communications, are widely used for our different daily needs. Examples are numerous and standard names like BLUETOOTH, WiFI, WiMAX, UMTS, GSM and, more recently, LTE are well-known [Baudoin et al. 2007]. General applications in the RFID or UWB contexts are the subject of many papers. This chapter presents radio-frequency (RF) communication systems architecture for mobile, wireless local area networks (WLAN) and connectivity terminals. An important aspect of today's applications is the data rate increase, especially in connectivity standards like WiFI and WiMAX, because the user demands high Quality of Service (QoS). To increase the data rate we tend to use wideband or multi-standard architecture. The concept of software radio includes a self-reconfigurable radio link and is described here on its RF aspects. The term multi-radio is preferred. This chapter focuses on the transmitter, yet some considerations about the receiver are given. An important aspect of the architecture is that a transceiver is built with respect to the radio-communications signals. We classify them in section 2 by differentiating Continuous Wave (CW) and Impulse Radio (IR) systems. Section 3 is the technical background one has to consider for actual applications. Section 4 summarizes state-of-the-art high data rate architectures and the latest research in multi-radio systems. In section 5, IR architectures for Ultra Wide Band (UWB) systems complete this overview; we will also underline the coexistence and compatibility challenges between CW and IR systems