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Embedded wireless sensor network (WSN) systems have been developed and used in a wide variety of applications such as local automatic environmental monitoring; medical applications analysing aspects of fitness and health energy metering and management in the built environment as well as traffic pattern analysis and control applications. While the purpose and functions of embedded wireless sensor networks have a myriad of applications and possibilities in the future, a particular implementation of these ambient sensors is in the area of wearable electronics incorporated into body area networks and everyday garments. Some of these systems will incorporate inertial sensing devices and other physical and physiological sensors with a particular focus on the application areas of athlete performance monitoring and e-health. Some of the important physical requirements for wearable antennas are that they are light-weight, small and robust and should also use materials that are compatible with a standard manufacturing process such as flexible polyimide or fr4 material where low cost consumer market oriented products are being produced. The substrate material is required to be low loss and flexible and often necessitates the use of thin dielectric and metallization layers. This paper describes the development of such a wearable, flexible antenna system for ISM band wearable wireless sensor networks. The material selected for the development of the wearable system in question is DE104i characterized by a dielectric constant of 3.8 and a loss tangent of 0.02. The antenna feed line is a 50 Ohm microstrip topology suitable for use with standard, high-performance and low-cost SMA-type RF connector technologies, widely used for these types of applications. The desired centre frequency is aimed at the 2.4GHz ISM band to be compatible with IEEE 802.15.4 Zigbee communication protocols and the Bluetooth standard which operate in this band.

International audience; Future mobile terminals will be able to communicate with various heterogeneous systems which are different by means of the algorithms used to implement baseband processing and channel coding.This represents many challenges in designing flexible and energy efficient architectures. Using the sensing phase, the mobile can sense its environment and detect the spectrum holes and use them to communicate. Current research are investigating different techniques of using cognitive radio to reuse locally unused spectrum to increase the total system capacity. They aim also to develop efficient algorithm able to maximize the quality of service (QoS) for the secondary (unlicensed) users while minimizing the interference to the primary (licensed)users. However, there are many challenges across all layers of a cognitive radio system design, from its application to its implementation.

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Field asymmetries in the rf coupler of accelerating structures degrade the projected beam transverse emittance, especially at low energy. This paper presents an alternative single feed coupler design that reduces the dipolar and the quadrupolar field components by exploiting a movable short circuit placed on the opposite waveguide. The structure has been simulated and optimized with the Ansys HFSS simulation code. RF measurements on an aluminum prototype machined in the "Elettra - Sincrotrone Trieste S.C.p.A.", are here presented. Such results are in good agreement with the simulations.

Diploma Thesis Summarization: The demand for larger bandwidth in wireless communications, motivates the RF circuit designers to advance to higher frequencies in order to serve the rapidly growing market. CMOS technology has dominated in the design of radio frequency and analog integrated circuits. Using devices in the nanometer regime, provides the possibility for greater operation frequencies and ultimately faster data rates. Additionally, RF circuit design is increasingly taking advantage of the aggressive scaling of submicrometer CMOS technologies that make possible the integration of complete tele-communication systems in a single chip (SoC). Low noise amplifiers (LNA) are one of the most important blocks of any telecommunication system. Their importance lies on the fact that they impact the noise performance more than any of the other blocks in the receiver chain. The main purpose of the low noise amplifier is to increase the power of the attenuated input signal, while at the same time minimizing the noise added to the chain by the circuit itself. In the RF design procedure, a designer faces the problem of trade-offs in quantities like consumption, gain, linearity etc. The purpose of this thesis is the introduction of a theoretical model that defines the optimum operation of a LNA (figure-of-merit) and afterwards the introduction of a design methodology that approaches the theoretical response. The thesis also proposes the integration of a genetic algorithm in the design sequence, that finds actual optimum solutions using the procedures of natural selection, reproduction and mutation. Finally, the efficiency of the equation model and genetic algorithm combination is showcased with the design of an optimum 5 GHz common source LNA. The optimal LNA design is obtained in the region of moderate inversion, according to both the analytical model and the optimization procedure. Furthermore, the other LNA topologies such as cascode LNA and common gate LNA are also evaluated. This work provides valuable insight into the design trade-offs of the different LNA topologies.