Radio coverage for emergency communication systems to operate under critical wildfire environments - TOOL

Publications

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.

2020-08Conference paper

Open access

Analysis of Radiowave Propagation in Forest Media Using the Parabolic Equation

Publication . Ramos, Glaucio L.; Pereira, Paulo T.; Leonor, Nuno; Caldeirinha, Rafael F. S.

This paper presents preliminary results about path loss prediction in vegetation using the parabolic equation technique. The trees were modelled in a flat and a triangular format and their effect in the path loss was analysed. A real measurement scenario with trees was also modelled and compared with the PE simulation. The use of the parabolic equation method to study the path loss attenuation in forest environments seems to be very promise.

2020-03Conference paper

Open access

A Practical Deconvolution Antenna Method to Retrieve Scattering Profile in Complex Random Media - A Vegetation Case Study at 28 GHz

Publication . Leonor, Nuno; Fernandes, Telmo; Caldeirinha, Rafael

This paper presents a method to improve the extraction the Radiative Energy Transfer (RET) theory input parameters for application in vegetation attenuation modeling. The input parameters for this model, which are extracted from specific measurement data, are normally influenced by the radiation pattern of the receiver antenna. A new method to improve the accuracy of the scattering function parameters obtained from measurements is presented. This method is based on the prior analysis of the antenna's radiation pattern distortion while measuring the scattering function, allowing the development of calibration curves, to correct the distorted propagation parameters. The proposed method was tested with measurements conducted inside an anechoic chamber, using real small indoor trees, mimicking a forest scenario using various different receiver antennas at 28 GHz, and the model accuracy improvement was assessed at various vegetation depths.

2020-03Conference paper

Open access