M. Bozzetti

Antennas and propagation for on-body communication systems

On-body communication channels are of increasing interest for a number of applications, such as medical-sensor networks, emergency-service workers, and personal communications. This paper describes investigations into channel characterization and antenna performance at 2.45 GHz. It is shown that significant channel fading occurs during normal activity, due primarily to the dynamic nature of the human body, but also due to multipath around the body and from scattering by the environment. This fading can be mitigated by the use of antenna diversity, and gains of up to 10 dB are obtained. Separation of the antennas performance from the channel characteristics is difficult, but results show that for many channels, an antenna polarized normal to the bodys surface gives the best path gain. Simulation and modeling present many challenges, particularly in terms of the problems scale, and the need for accurate modeling of the body and its movement.

A Broadband Pattern Diversity Annular Slot Antenna

An annular slot antenna suitable for pattern diversity in wideband applications is presented. Pattern diversity is obtained by feeding the antenna simultaneously with two microstrip lines printed on the back of the substrate, which generate orthogonal radiation patterns. Two shorts placed at 45 degrees between the microstrip lines and in the opposite direction ensure an isolation above 15 dB according to measurements. The antenna operates in the range of frequencies from 3 GHz to 12 GHz (1:4 bandwidth) and covers many different standards (Wireless-LAN, HIPERLAN2, WIMAX, UWB). Simulations and measurements for return loss, isolation and radiation patterns are presented. Furthermore, measurements have been carried out in a real multipath environment in order to evaluate pattern diversity performance. Results of measurements of the correlation coefficient and diversity gain over the entire operating bandwidth show that the antenna is suitable for antenna diversity systems.

Simulation and Measurement of Dynamic On-Body Communication Channels

A study is presented of wireless on-body communication links, with the body in motion. This paper compares simulations and measurements of the path gain (PG) on moving male and female bodies. Simulations using avatars derived from an animation software have been performed at 2.45 GHz. Male and female avatars walking and a male rising from a chair have been simulated and the results are compared with measurements carried out in an anechoic chamber. The results show that good agreement between simulation and measurement of slow fading features can be achieved for a reasonable computational effort.

Use of Animation Software in Simulation of On-Body Communications Channels at 2.45 GHz

As wearable electronic devices become increasingly popular, there is a growing interest in the design of body area networks (BAN). The propagation characteristics of such channels are of interest to assist in proper design of BAN systems. It has been shown that body movement is a primary factor in channel fading and hence channel modelling must include the effect of movement. In this letter, results are presented for a walking phantom created using animation software. Simulations of a walking avatar for three different channels at a frequency of 2.45 GHz are shown and compared to measurements made on a human body in an anechoic chamber. It is shown that such a phantom can give good prediction of mean and standard deviation of the propagation channel of a walking subject.

Use of Animation Software in the Simulation of On-Body Communication Channels

Wireless Body Area Networks (WBANs) promise cheap and unobtrusive interconnections of electronic based sensors, processors and other devices during normal daily activities in personal, military and sports use. However the modelling of body dynamics raises difficulties when simulation of the channels is required. In this paper the activity of walking has been studied, through the combination of animation and electromagnetic software. Simulations of a walking male at the frequency of 2.45 GHz for two different channels are presented and these results are compared with measurements made in anechoic chamber.

An analytical 3D model of metal foams for EM shielding applications

In this paper a preliminary electromagnetic shielding behaviour of metal foams, is developed and discussed. Metal foams represent a novel class of materials which promise new interesting properties employable for various purposes. More specifically, the realization of electromagnetic shields has been considered and experimental Shielding Effectiveness (SE) measurements have been performed, demonstrating very good performance. In order to allow the design of metal foam EM shields, double 3D wire-mesh screens, obtained as a development of a previously 2D laminated shield, has been presented, comparing the relative results with experimental measure. The good agreement among the preliminary data paves the way to obtain an efficient analytical model of the complex electromagnetic behavior of metal foams.

Design of a dielectric applicator for microwave heating.

In this paper the design of a handheld light applicator for microwave heating is presented. The applicator is made of an array of resonant longitudinal slots cut on a broad wall of a rectangular waveguide, and it is covered by a cylindrical lens made of Plexiglas with a permittivity of 2.53. The geometrical optics approach is used as initial approximation to establish the lens profile. It allows for the shaping of the slotted waveguide’s radiation pattern into a desired output pattern in the transversal plane. Three-dimensional simulation results show that the applicator performance can be improved at 2.45 GHz by using a homogeneous dielectric lens.

Mode-stirred chamber for cereal disinfestation

Abstract A new microwave technique is proposed in order to prevent the growth of and/or eliminate parasites that infest cereals while they are being stocked in the mills. The investigated microwave system is made of a mode-stirred chamber suitably designed in order to be applied in the cereal industrial working chain without a drastic breakpoint. A dedicated computer code, based on the Transmission Line Matrix method, has been suitably implemented in order to design the particular geometry of the stirrers, to evaluate the microwave characteristics of the resonant cavity, and to identify the best conditions for the electromagnetic field uniformity in the region where the cereals run.

Integrated Vivaldi antennas, an enabling technology for optical wireless networks on chip

In this paper, we propose an integrated Vivaldi antenna, coupled to a silicon waveguide, for wireless Optical Network-on-Chip applications. On-chip wireless propagation characteristics and point-to-point link performances in homogeneous and multilayered medium are investigated and discussed as well. The proposed structure allows the implementation of wireless communication at optical frequencies and it can lead to a completely new approach in network design, allowing hybrid wireless/wired communications on the same die. This hybrid solution, in fact, can mitigate the problems related to the design and the fabrication of complex switching matrices in large networks, where long paths suffer of crosstalk and loss issues.

Coupling between Si-waveguides and plasmonic antennas for optical networks on chip

On-chip wireless optical communications among distant cores in chip multiprocessors can lead to a completely new approach to the limits of current on-chip communication. In fact, using wireless connections mitigates the problems related to the design and the fabrication of hugely complex switching fabrics, where long paths suffer of crosstalk and loss issues. We investigate the possibility of integrating plasmonic nanoantennas and silicon waveguides to allow the compatibility with optical networks and devices. In particular, we report the numerical analysis of a plasmonic Vivaldi antenna coupled to a silicon waveguide. The design criteria and the radiation characteristics are described.