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About

About

I am a senior researcher at the Centre of Telecommunications and Multimedia of INESC TEC, where I am also the coordinator of the area of Optical and Electronic Technologies. I received the “Licenciatura” degree in 2006 and PhD degree in 2011, both in Electrical and Computer Engineering from the Faculty of Engineering of the University of Porto. Currently I am responsible for the conception and management of R&D projects, coordination of research students and fostering the valorization of research results through new contracts with industry. I was previously involved in teaching of RF/microwave engineering and optical communications as an invited assistant professor at the University of Porto. I am author/co-author of more than 50 publications in international conferences and journals with peer-review, and 1 european patent. I have coordinated several research projects and participated in several EU research projects. My main research interests include coherent optical systems, radio-over-fibre, RF/microwave devices and antennas, and underwater wireless power/communications.

Interest
Topics
Details

Details

022
Publications

2023

Misalignment-Resilient Propagation Model for Underwater Optical Wireless Links

Authors
Araujo, JH; Tavares, JS; Marques, VM; Salgado, HM; Pessoa, LM;

Publication
SENSORS

Abstract
This paper proposes a multiple-lens receiver scheme to increase the misalignment tolerance of an underwater optical wireless communications link between an autonomous underwater vehicle (AUV) and a sensor plane. An accurate model of photon propagation based on the Monte Carlo simulation is presented which accounts for the lens(es) photon refraction at the sensor interface and angular misalignment between the emitter and receiver. The results show that the ideal divergence of the beam of the emitter is around 15° for a 1 m transmission length, increasing to 22° for a shorter distance of 0.5 m but being independent of the water turbidity. In addition, it is concluded that a seven-lense scheme is approximately three times more tolerant to offset than a single lens. A random forest machine learning algorithm is also assessed for its suitability to estimate the offset and angle of the AUV in relation to the fixed sensor, based on the power distribution of each lens, in real time. The algorithm is able to estimate the offset and angular misalignment with a mean square error of 5 mm (6 mm) and 0.157 rad (0.174 rad) for a distance between the transmitter and receiver of 1 m and 0.5 m, respectively.

2023

Self-Localization via Circular Bluetooth 5.1 Antenna Array Receiver

Authors
Paulino, N; Pessoa, LM;

Publication
IEEE ACCESS

Abstract

2022

Proof of Concept of a Low-Cost Beam-Steering Hybrid Reflectarray that Mixes Microstrip and Lens Elements Using Passive Demonstrators

Authors
Luo, Q; Gao, S; Hu, W; Liu, W; Pessoa, LM; Sobhy, M; Sun, YC;

Publication
IEEE COMMUNICATIONS MAGAZINE

Abstract
In this article, a proof-of-concept study on the use of a hybrid design technique to reduce the number of phase shifters of a beam-scanning reflectarray (RA) is presented. An extended hemispherical lens antenna with feeds inspired by the retrodirective array is developed as a reflecting element, and the hybrid design technique mixes the lenses with the microstrip patch elements to realize a reflecting surface. Compared to the conventional designs that only use microstrip antennas to realize a reflecting surface, given a fixed aperture size the presented design uses 25 percent fewer array elements while shows comparable beam-steering performance. As a result of using fewer elements, the number of required phase shifters or other equivalent components such as RF switches and tunable materials is reduced by 25 percent, which leads to the reduction of the overall antenna system's complexity, cost, and power consumption. To verify the design concept, two passive prototypes with a center frequency at 12.5 GHz were designed and fabricated. The reflecting surface was fabricated by using standard PCB manufacturing and the lenses were fabricated using 3D printing. Good agreement between the simulation and measurement results is obtained. The presented design concept can be extended to the design of RAs operating at different frequency bands including millimetre-wave frequencies with similar radiation performances. The presented design method is not limited to the microstrip patch reflecting elements and can also be applied to the design of the hybrid RAs with different types of reflecting elements.

2022

A Gaussian Window for Interference Mitigation in Ka-band Digital Beamforming Systems

Authors
Tavares, JS; Avelar, HH; Salgado, HM; Pessoa, LM;

Publication
2022 13th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2022

Abstract

2022

Design and Experimental Evaluation of a Bluetooth 5.1 Antenna Array for Angle-of-Arrival Estimation

Authors
Paulino, N; Pessoa, LM; Branquinho, A; Gonçalves, E;

Publication
13th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2022, Porto, Portugal, July 20-22, 2022

Abstract
One the of the applications in the realm of the Internet-of-Things (IoT) is real-time localization of assets in specific application environments where satellite based global positioning is unviable. Numerous approaches for localization relying on wireless sensor mesh systems have been evaluated, but the recent Bluetooth Low Energy (BLE) 5.1 direction finding features based on Angle-of-Arrival (AoA) promise a low-cost solution for this application. In this paper, we present an implementation of a BLE 5.1 based circular antenna array, and perform two experimental evaluations over the quality of the retrieved data sampled from the array. Specifically, we retrieve samples of the phase value of the Constant Tone Extension which enables the direction finding functionalities through calculation of phase differences between antenna pairs. We evaluate the quality of the sampled phase data in an anechoic chamber, and in a real-world environment using a setup composed of four BLE beacons. © 2022 IEEE.

Supervised
thesis

2022

Desenvolvimento de Uma Antena em Grafeno

Author
Luís Pedro Silva Ermida Martins de Freitas

Institution
UP-FEUP

2022

Desenvolvimento de Uma Antena Inteligente Para 28 GHz

Author
Margarida Granja Costa

Institution
UP-FEUP

2022

Ultra Flexible RF Electronics: Performance Study of Lines and Antennas

Author
Rafael Perez morais

Institution
UP-FEUP

2021

Next Generation Long-Haul Optical Fibre Communications and Optical-Wireless Interfaces

Author
Joana dos Santos Tavares

Institution
UP-FEUP

2021

Vehicle Tracking in Warehouses via Bluetooth Beacon Angle-of-Arrival

Author
Telmo Francisco da Costa Soares

Institution
UP-FEUP