Percorrer por autor "Fernandes, Telmo Rui"
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- 3D Indoor Radio Coverage for 5G Planning: a Framework of Combining BIM with Ray-tracingPublication . Louro, João; Fernandes, Telmo Rui; Rodrigues, Hugo; Caldeirinha, Rafael F. S.This paper presents a framework to predict indoor radio wave coverage in buildings. Such method includes the capability to import BIM (Building Information Modelling) files that contain structured physical geometry and dimension data, including the material types that are of uttermost importance in evaluating their dielectric properties. Appropriated extraction of physical and dielectric attributes of the building elements was used as input to a 3D radio wave propagation ray-tracing developed in MatLab that allows the prediction of the received radio signal level at any location within the computational volume. Results are presented for line-of-sight contributions and first and second order reflections. Despite the generic nature of the proposed framework, prediction results are presented at 3.6 GHz, envisaging emerging 5G indoor radio coverage.
- Building Information Modelling Conversion for Radiowave Propagation StudiesPublication . Louro, João; Fernandes, Telmo Rui; Rodrigues, Hugo; Caldeirinha, RafaelThis paper presents a Building Information Modelling (BIM) data conversion algorithm for radio wave propagation studies in indoor and outdoor environments. The tool presented here allows to extract the geometrical and physical information of BIM models present in IFC2×3 files. The first conversion step is done using the IFCOpenSHell library through a Python interface and the second one is done using MatLab. Following MatLab results extraction, studies of propagation will proceed. The extracted information allows ray tracing simulations and/or radiowave propagation studies through a real-scale simulation scenarios, spending less computational time. The results presented refer to a small wooden house for a frequency of 3.6 GHz, for 5G, using a directional transmitter antenna and an omnidirectional receiving antenna. It is possible to check the result for the direct component and first, second and third order reflections.
- Metamaterial-Inspired Flat Beamsteering Antenna for 5G Base Stations at 3.6 GHzPublication . Reis, João Ricardo; Vala, Mário; Oliveira, Tiago Emanuel; Fernandes, Telmo Rui; Caldeirinha, Rafael Ferreira SilvaIn this paper, a metamaterial-inspired flat beamsteering antenna for 5G applications is presented. The antenna, designed to operate in the 3.6 GHz at 5G frequency bands, presents an unique flat form factor which allows easy deployment and low visual impact in 5G dense scenarios. The antenna presents a multi-layer structure where a metamaterial inspired transmitarray enables the two-dimensional (2D) beamsteering, and an array of microstrip patch antennas is used as RF source. The use of metamaterials in antenna beamsteering allows the reduction of costly and complex phaseshifter networks by using discrete capacitor diodes to control the transmission phase-shifting and subsequently, the direction of the steering. According to simulations, the proposed antenna presents steering range up to ±20◦, achievable in both elevation and azimuth planes, independently. To prove the concept, a prototype of the antenna has been built and experimentally characterised inside an anechoic chamber. Although constructed in a different substrate (FR4 substrate) as initially designed, beamsteering ranges up to 8◦ in azimuth and 13◦ in elevation, limited to the proposed case-studies, are reported with the prototype, validating the antenna and the usefulness of the proposed design.
- Tunable square slot FSS EC modelling and optimisationPublication . Ferreira, David; Caldeirinha, Rafael Ferreira Silva; Cuiñas, Iñigo; Fernandes, Telmo RuiAn equivalent circuit model for tunable square slot frequency selective surfaces (FSS) is proposed. Tuning is achieved with the inclusion of a discrete capacitance element, at key points within the FSS unit cell. The equivalent circuit model takes into account the FSS physical attributes. The performance of the proposed equivalent circuit model was evaluated against results obtained from appropriate electromagnetic simulations. Results demonstrate the validity of the proposed equivalent circuit model, in which good estimations of the frequency response of FSS structures were obtained. A RMSE value of 190 MHz was extracted from the complete parametric simulation set. The model was further validated against measurements performed on a tunable active FSS prototype inside an anechoic chamber. Tuning of the FSS was achieved by means of bias voltage to modify the varicaps capacitance value. A relatively good agreement was verified between equivalent circuit model, electromagnetic simulations and measurements. Finally, this work is sought to be a useful contribution to the literature on this topic, by improving on the elementary models of such FSS structures and be useful as a good and fast first approach to determine approximate FSS unit cell dimensions.