RT Dissertation/Thesis
T1 RF transparency control of building wall structures
T2 Control da transparencia en radiofrecuencia de estruturas construtivas de paredes
A1 Crespo Ferreira, David
K1 3307.08 Dispositivos de Microondas
K1 2202.10 Radioondas y Microondas
AB This Ph.D work was aimed at studying new propagation enhancement (and reduction) techniques using Frequency Selective Surfaces (FSS) for interference mitigation and Wireless security in indoor radio environments. The concept of controlling radio frequency transparency of building wall structures was analyzed, with a focus on Southern European architecture, and it was demonstrated that some building materials exhibit a significant impact on wireless propagation.The wireless transmission properties of hollow clay brick and concrete walls, traditionally employed in European residential constructions, were measured in an anechoic chamber.The studies performed to better understand the observed penetration losses associated with such clay bricks, culminated in the proposal of an alternative brick design, yielding reduced penetration losses compared to classical ones at several frequency bands, such as the commercial WiFi band.FSS are envisaged to be deployed to either selectively confine radio propagation in indoor areas, by artificially increasing the radio transmission loss naturally caused by building walls, or to guide radio signals into other areas of interest. The development and deployment of new FSS structures was addressed through theoretical investigations as well as experimental data gathering and model validation at various frequencies,from 400MHz up to 10GHz. FSS manufacturing materials and production methods were addressed, gathering some of the most relevant solutions published by the scientific community. Several FSS designs were modeled and validated inside an anechoic chamber,including the innovative 3D mechanically tunable FSS based on a 2D canonical design.A hybrid FSS and rectenna design was also investigated for wireless power harvesting of ambient RF energy.This work culminates with analysis of the different elements required to modify the EM transparency of building wall layers: i) different methods to control the frequency selectivity are identified with a focus on FSS; ii) some proposals on the integration of FSS on current and new building structures are provided; iii) measurement results are presented regarding the penetration losses of multi-layered wall samples; and iv) a multilayer EM simulation tool, developed in Matlab, is introduced and validated against measurement results, allowing the simulation and analysis of additional, user-defined,scenarios.
YR 2017
FD 2017-11-17
LK http://hdl.handle.net/11093/892
UL http://hdl.handle.net/11093/892
LA eng
DS Investigo
RD 12-may-2025