1,721,147 research outputs found
La componente tecnologica nell’architettura
No full textGli aspetti relativi alle risoluzioni costruttive nella tradizione e nella contemporaneità sono affrontati nell'ottica di una valutazione finalizzata alla didattic
Insediamento e popolazione
No full textLo studio riguarda la trasformazione dell'edificato in funzione delle variazione dell'assetto demografico del luogo, nel periodo tra XIX e fine del XX secolo
Scale model investigation of mechanisms for scattering from office buildings at 2 GHz
No full textIn this work, a 60 GHz empirical investigation on a scale model is performed to give insight into building scattering at 2 GHz. From the presented building scattering measurements, the relative effects of the furniture and building surface on the building scattered signal are determined. The fading statistics of the scattered signal are also determined and are found to be Rayleigh distributed. Lastly, a simple method to compute the scattered power from a building using the effective roughness approach is presented and validated using the measurements
Analysis of Mm-Wave Scattering from Construction Materials
No full textMM-wave frequency bands at around 27 and 38 GHz have been recently allocated to 5G communications and therefore the characterization of transmission, reflection and scattering characteristics of building materials at those frequencies is in the spotlight. Scattering from common construction materials is analysed in the paper through both directional measurements and simulations. Differently from common sentiment, it is shown that 27 GHz waves can penetrate into walls and scattering from internal structures can be relevant, especially in the case of Gypsum board dividing walls. It is shown that back-scattering can be modelled with the double lobe version of the Effective Roughness model for 3 very common construction materials, with different parameters depending on the material
Semi-Deterministic Radio Channel Modelling Based on Graph Theory and Ray-Tracing
Full text linkGraph theory channel modelling is an efficient approach to simulate multipath radio propagation including the reverberation effect of electromagnetic waves. In this contribution, without modifying the modelling framework, we proposed a semi-deterministic channel modelling approach by associating the scatterers with realistic environment objects, and by calculating the coefficients of the propagation paths on the base of a physically sound and proven diffuse scattering theory. The diffuse multipath components are then combined with the specular components simulated by ray-tracing to obtain a complete channel representation. The proposed method is evaluated in two reference scenarios at 3.8 and 60 GHz respectively by comparing the simulated channel characteristics with channel measurement data. Results show that the proposed method can accurately predict the channel characteristics in both the delay domain and the angular domain. The proposed approach is appropriate to model multipath propagation in confined indoor or dense-urban environment at millimeter-wave frequencies and above, where reverberation and rough-surface scattering can be important phenomena
Analysis and Modeling of the Polarization Characteristics of Diffuse Scattering in Indoor and Outdoor Radio Propagation
No full textThe polarimetric properties of the radio channel, with particular reference to the Dense Multipath
Components (DMC), are analyzed in the present work for different types of outdoor and indoor environments,
with the aid of measurements and Ray Tracing (RT) simulations. A heuristic Diffuse Scattering model, suitable
to be embedded in RT tools, is properly tuned and parameterized to reproduce the cross-polar discrimination
(XPD) characteristics of the DMC extracted from measurement data in the above mentioned scenarios
Use of a Realistic Ray-Based Model for the Evaluation of Indoor RF Coverage Solutions Using Reconfigurable Intelligent Surfaces
Full text linkA previously developed Huygens-based, “antenna-array-like” macroscopic model for scattering from metasurfaces is embedded into a ray-tracing tool and used to carry out realistic RF-coverage evaluations in indoor environment. Using the reciprocity of the link, we extend prediction to multiple-bounce paths that include metasurface scattering at the beginning or at the end of the interaction chain. The proposed model allows us to carry out coverage evaluations for any realistic RIS design by modifying a few simple parameters. In this work, reference environments such as T–shaped and L–shaped corridor cases are considered with different deployment solutions of anomalous and focusing reflectors. The results show that a gain of about 15–20 dB can be obtained in blind-spot locations with proper RIS placement and configuration, without the use of any additional active radio head, even when using simple designs such as pre-configured lossy phase-gradient metasurfaces
A study on polarimetric properties of scattering from building walls
No full textThe polarimetric characteristics of the signal back
scattered from a building wall are studied in this paper with
the aid of MIMO measurements and Ray Tracing simulation.
A very simple environment with a single building amid an
open area is considered to reduce complexity and better isolate
the different kinds of back-scattered contributions: specular
reflection, diffractions, diffuse scattering. A high degree of crosspolarization
coupling, largely due to diffused scattering phenomena,
is generally observed. Moreover the diffuse component
represents about 30% of the total backscattered power even in
such a simple topology
A Reciprocal Heuristic Model for Diffuse Scattering from Walls and Surfaces
Full text linkDiffuse scattering of electromagnetic waves from natural and artificial
surfaces has been extensively studied in various disciplines, including radio
wave propagation, and several diffuse scattering models based on different
approaches have been proposed over the years, two of the most popular ones
being Kirchhoff Theory and the so-called Effective Roughness heuristic model.
The latter, although less rigorous than the former, is more flexible and
applicable to a wider range of real-world cases, including non-Gaussian
surfaces, surfaces with electrically small correlation lengths and scattering
from material inhomogeneities that are often present under the surface.
Unfortunately, the Effective Roughness model, with the exception of its
Lambertian version, does not satisfy reciprocity, which is an important
physical-soundness requirement for any propagation model. In the present work,
without compromising its effectiveness and its simple and yet sound
power-balance approach, we propose a reciprocal version of the Effective
Roughness model, which can be easily implemented and replaced to the old
version in ray-based propagation models. The new model is analyzed and compared
to the old one and to other popular models. Once properly calibrated, it is
shown to yield similar - if not better - performance with respect to the old
one when checked vs. measurements
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