Small but long koch fractal monopole

A small but long wire fractal antenna based on the Koch curve is presented. Experimental and numerical results show that the antenna improves the features of a common linear monopole. The radiation resistance is increased and the Q is reduced at each fractal iteration, approaching the fundamental limit on small antennas.Peer ReviewedPostprint (published version

Sistema lidar elástico incoherente para sondeo de la atmósfera

The main features of the incoherent elastic lidar operating at the premises of the Department of Signal Theory and Communications' Electroinagnetic and Photonics Engineering Group, in the Campus fiord of the Polytechnic University of Catalonia, are presented. The system is able to detect atmospheric acrosols (dust, haze, smoke...) and to prende data about the structure of clouds. Its performance is shown in the forro of results concerning the measurement of atmospheric extinction and backscatter coefficients for severa' atmospheric conditions.Peer ReviewedPostprint (published version

Sobolev spaces on non-Lipschitz subsets of Rn with application to boundary integral equations on fractal screens

We study properties of the classical fractional Sobolev spaces on non-Lipschitz subsets of Rn. We investigate the extent to which the properties of these spaces, and the relations between them, that hold in the well-studied case of a Lipschitz open set, generalise to non-Lipschitz cases. Our motivation is to develop the functional analytic framework in which to formulate and analyse integral equations on non-Lipschitz sets. In particular we consider an application to boundary integral equations for wave scattering by planar screens that are non-Lipschitz, including cases where the screen is fractal or has fractal boundary

Statistical analysis of particle distributions in composite materials

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN041905 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Ground plane boosters to provide multi-band operation in wireless handheld devices

Recent demand for multifunctional wireless devices has increased the challenge for the antenna designe rs, who has to address it by providing small antennas able to oper ate in multiple communication standards. This paper propos es a new generation of radiating systems capable of providin g multi-band operation without the need of including a dedicated antenna. The solution is based on the excitation of a structure already existing in any wireless handheld device, the ground plane. Said excitation is carried out through a pair of booster s with dimensions 5 mm x 5 mm x 5 mm, especially designed to transfer the maximum power to the efficient ground plane rad iation mode. In addition, a radiofrequency system is combi ned with the booster-based radiating structure in order to provi de penta-band operation. The feasibility of the proposal has been tested by electromagnetic simulations as well as by experimen tal measurements. Furthermore the human head interactio n concerning Specific Absorption Rate (SAR) has been analyzed and a proposal for its reduction is presented. As a result a promising standard solution for a radiating system capable to operate in the main communication standards GSM850, GSM900, DCS, PCS and UMTS is provided with a volume reduction factor around 20 compared with current te chnologiesPeer Reviewe

Ground plane boosters to provide multi-band operation in wireless handheld devices

Recent demand for multifunctional wireless devices has increased the challenge for the antenna designe rs, who has to address it by providing small antennas able to oper ate in multiple communication standards. This paper propos es a new generation of radiating systems capable of providin g multi-band operation without the need of including a dedicated antenna. The solution is based on the excitation of a structure already existing in any wireless handheld device, the ground plane. Said excitation is carried out through a pair of booster s with dimensions 5 mm x 5 mm x 5 mm, especially designed to transfer the maximum power to the efficient ground plane rad iation mode. In addition, a radiofrequency system is combi ned with the booster-based radiating structure in order to provi de penta-band operation. The feasibility of the proposal has been tested by electromagnetic simulations as well as by experimen tal measurements. Furthermore the human head interactio n concerning Specific Absorption Rate (SAR) has been analyzed and a proposal for its reduction is presented. As a result a promising standard solution for a radiating system capable to operate in the main communication standards GSM850, GSM900, DCS, PCS and UMTS is provided with a volume reduction factor around 20 compared with current te chnologiesPeer ReviewedPostprint (published version

On the radiation psttern of the L-shaped wire antenna

An objective of the present study is to make a physical insight into the radiation properties of an L-shaped wire antenna. More specifically, the study is focused on the effects of the antenna geometry over the characteristic radiation pattern of an L-shaped wire antenna. Regarding the basic equations for the radiated field, three main regions according to the length-height ratio of an L-shaped wire antenna have been determined. The said regions depict the geometrical boundaries where the L-shaped wire antenna loses its characteristic monopoletype radiation pattern. In this sense and relating to the aspect ratio of the L-shaped antenna, the said radiation properties can be easily varied in order to achieve a half isotropic radiation pattern or even, a patch-type radiation pattern. Thus, the method described herein demonstrates that simple modifications applied to the geometry of a basic structure, allow obtaining radiation properties associated to more complex structures.Peer Reviewe