Serge Bories

Robust planar stripline monopole for UWB terminal applications

A fully planar UWB monopole with dual feed is designed for low cost applications over the [3.1-6] GHz frequency band. The achieved input bandwidth is [2.9-7.9] GHz for a size of 40 /spl times/ 24 /spl times/ 3 mm. The chosen stripline technology allows feeding circuit isolation from antenna radiation, and provides robustness to the 20 mm height protruding square-like monopole. The main drawback of such a fully planar design is the degradation of the omni-directionality beyond the first octave. The frequency radiation pattern dependency is investigated and evaluated with specific UWB characterization tools. At last a comparison between 2 monopoles with different technologies helps to settle the compromise between complexity/cost and global performance.

A Channel-Based Statistical Approach to Antenna Performance in UWB Communications

An analysis of the joint antenna-channel problem in ultrawideband communications is carried out in order to provide tools for the performance evaluation of antennas while taking into account the system architecture and the radio link scenarios. Owing to the stochastic character of channels and of antenna close environment, a statistical approach to the problem based on discrete channel models is favored. The distinction between gain and dispersion effects is highlighted, both in a nondirectional and in a fully directional channel model. It is shown that antenna distortion generally has a small effect, but for coherent pulse detection it provides an extra gain in dense multipath channels with respect to ideal antennas and low density channels

Probe fed stacked patch antenna for UWB

A microstrip patch antenna with two E-shaped stacked patches for UWB sectoral applications is proposed in this paper. The E-shaped patch antenna has an impedance bandwidth of about 34%. By adding a second E-shaped patch at the top of the first patch a bandwidth of 54% has been obtained. The characteristic dimensions of the second patch as well as the shift between the two patches have been optimized to achieve the ultra-wide bandwidth and radiation pattern stability over the whole band. The distorting nature of this antenna has been quantified using time domain characterization tools and the influence of the ground plane on impedance bandwidth and radiation has been studied.

A deterministic indoor UWB space-variant multipath radio channel modelling compared to measurements on basic configurations

A comparison of measured ultrawideband (UWB) signals and signals simulated by a ray-tracing tool are presented in the paper. The simulation tool is a full 3D indoor deterministic simulator aimed at illustrating low or high bit data rates channel parameters. The physical phenomena intervening in the complex indoor (multipath, shadowing) may be analysed by this means. A measurement campaign aimed at collecting ultrawideband signals in basic transmitter-receiver (Tx-Rx) configurations has been carried out. Simulated and measured signals are thus compared in terms of Impulse Responses and metrics like path losses, energy and delay spread. The work indicates that the deterministic ray-tracing approach can provide useful information for the system designer, especially if it is combined with statistical parameters.

UWB Antenna Performance Evaluation from the Communication System Point of View

This work discusses the performance of ultra wide band antennas in the context of communication systems. An analysis of the physical origins of antenna imperfections is first presented, followed by the definition of modulation and detection scheme dependent radiation patterns. The extension of the analysis to radio links involving a multipath channel is then carried out. The discussion is supported by a variety of antenna measurements and simulations, and makes use of an angular statistical multipath channel model.

UWB Antennas in Body Area Networks

The behavior of different UWB antennas in an on-body scenario is analyzed. Different orientations of directional antennas and different spacings between planar antennas and the body are investigated. Time domain channel parameters, e.g. mean delay and delay spread, are extracted from measurement data. The distribution of the channel parameters allows classification of the different antennas with respect to each parameter.

Dual stripline fed metal sheet monopoles for UWB terminal applications

An UWB planar monopole with dual stripline fed (matched over a 3.2–9.2 GHz bandwidth) is designed for low cost applications with an achieved input bandwidth of [3.2–9.2] GHz and size of (30×31×3 mm). The main drawback of such a fully planar design is the degradation of the omni-directionality beyond the first octave. The addition of simple orthogonal elements onto the monopole offers a very simple way to significantly reduce this effect. The improvements have been evaluated with specific UWB characterization tools.

SOI CMOS tunable capacitors for RF antenna aperture tuning

This paper provides a detailed analysis of a SOI CMOS tunable capacitor for antenna tuning. Design expressions for a switched capacitor network are given and quality factor of the whole network is expressed as a function of design parameters. Application to antenna aperture tuning is described by combining a 130 nm SOI CMOS tunable capacitor with a printed notch antenna. The proposed tunable multiband antenna can be tuned from 420 MHz to 790 MHz, with an associated radiation efficiency in the 33-73% range.

Semi-directional small antenna design for UWB multimedia terminals

The design and results of a new UWB printed dipole antenna with a dielectric lens are presented.

Compact dipole for low frequency band UWB applications

This paper presents a compact Ultra Wide Band (UWB) antenna designed to operate at lower than 1 GHz frequencies. Based on a particular physical interpretation of the antenna working mode illustrated by an equivalent wide band circuit model, specific developments have been carried out to miniaturize the antenna and to keep the wide band behaviour with slightly altered radiation efficiency. Time domain descriptors have been used to estimate the antenna ability to transmit short electromagnetic pulse. Antenna prototypes have been specifically designed to be used in a hand-held UWB system that enables a real-time positioning of multiple disaster victims such as avalanches, earthquakes, or burning buildings.