Logo do repositório

Percorrer por autor "Coimbra, Pedro"

A mostrar 1 - 2 de 2
  • Comparative Study of Computational Electromagnetics Applied to Radiowave Propagation in Wildfires
    Publication . Faria, Stefânia; Vala, Mário; Coimbra, Pedro; Felício, João; Leonor, Nuno; Fernandes, Carlos; Salema, Carlos; Caldeirinha, Rafael
    In this paper, a comparative study of four computational electromagnetic techniques to model the 2-dimensional radiowave propagation phenomena in wildfires, is proposed. The fire dynamics for a small tree specimen is studied, in which gases released from the combustion process are used to investigate the generation of an ionised plasma and, thus, to evaluate the gradient of the medium refractive index using the cold plasma model. Consequently, the presence of fire has been demonstrated to introduce additional losses in the radio path that may be critical to radio communication systems that are widely used in mission critical applications. The gradient of the refractive index across the vegetation volume yielded by the cold plasma model is used as input parameter to different numerical methods and electromagnetic solvers at 385 MHz (i.e. TETRA frequency band in Portugal) and, subsequently, their applicability to wildfires is assessed.
    2020-08Comunicação em conferência Acesso aberto Ver mais
  • Experimental Setup for Radio Characterization of Fire at Microwave Frequencies
    Publication . Coimbra, Pedro; Faria, Stefânia; Vala, Mário; Felício, João; Fernandes, Carlos; Leonor, Nuno; Caldeirinha, Rafael; Salema, Carlos
    Wildfires are a recurring phenomenon in many countries around the world, either due to natural causes or negligent human behavior. Emergency communication services used by firefighters at the theater of operations must be highly reliable, in order to ensure the safety and coordination of the teams that are fighting the wildfire, contributing to extinguishing it as quickly as possible with minimum use of resources. Emergency communication networks strongly rely on wireless links that may be impaired by the flames. In this work, we present an experimental setup for characterization of fire at microwave frequencies. Preliminary results show that we are able to extract very low dielectric constant (<1.1) using ultrawideband signals. Moreover, we characterize the attenuation introduced by fire in small-scale scenario. Future work will include the characterization of fire in larger-scale scenarios.
    2021-02Comunicação em conferência Acesso restrito Ver mais