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About

About

Henrique M. Salgado graduated in Applied Physics (Optics and Electronics) from the University of Porto in 1985 and received the PhD degree in Electronic Engineering and Computer Systems from University of Wales in 1993. He joined the Department of Electrical Engineering and Computers of the University of Porto in 1999 as an Invited Assistant Professor and in 2003 he became Associate Professor. Since 1995 that he heads the Optical and Electronics Area of INESC TEC, begin responsible for several national and internationally funded (EU) research projects. From 1997-1999 he was Research Fellow at the Department of Electrical and Electronic Engineering of the University College London, UK and previously Research Assistant at the School of Electronic Engineering and Computer Systems, Bangor, UK. He is the author and co-author of numerous international publications in the field of optical fibre communications and microwaves. His current research interests include: radio-over-fiber technology and microwave photonics, digital equalization in coherent optical systems, all-optical networks, modeling of nonlinearities and design of compact multiband antennas. He is a member of the Photonics and Communications societies of the IEEE.

Interest
Topics
Details

Details

  • Name

    Henrique Salgado
  • Role

    Senior Researcher
  • Since

    25th October 1985
024
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 degrees for a 1 m transmission length, increasing to 22 degrees 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

Sigma-Delta Modulation for Enhanced Underwater Optical Wireless Communication Systems

Authors
Araújo J.H.; Rocha H.J.; Tavares J.S.; Salgado H.M.;

Publication
International Conference on Transparent Optical Networks

Abstract
This paper presents an experimental investigation of sigma-delta modulation (SDM) as a means of improving the performance of underwater optical communication systems. The study considers the impact of the key parameters of SDM, including oversampling ratio, the system's signal-to-noise ratio, bandwidth, and optical link distance. The results of this study provide insights into the design and optimization of SDM-based underwater optical communication systems, paving the way for future research in this field. A fully digital solution, albeit operating at a lower bit rate than previously published OFDM counterparts, provides immunity against nonlinearities of the system and robustness to noise, which is relevant in harsh environments. Moreover, the proposed solution based on a first-order bandpass SDM architecture avoids the employment of a DAC at the receiver, simplifying its operation and reducing costs. An experimental investigation is carried out for the transmission of 16-QAM over SDM, and a transmission distance of 4.8 m over the underwater channel is achieved with a maximum transmission rate of 400 Mbit/s with an MER of 28 dB.

2022

Substrate Integrated Waveguide Cavity Backed Slot Antennas for Millimeter-Wave Applications

Authors
Finich, S; Salgado, HM; Pinho, P;

Publication
2022 16TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP)

Abstract
A low-cost single-layer substrate-integrated waveguide (SIW) cavity-backed slot antenna is proposed for millimeter-wave applications. The structure is designed to operate at the W-band. The T-shaped slot antenna is placed on the back-side of the SIW and fed by a grounded coplanar waveguide (GCPW) transmission line. A transition between the (GCPW) and the SIW is also designed. The simulated results provide that the antenna has a stable gain over the frequency range (98.79-100.56) GHz with a maximum value of around 6 dBi also high radiation efficiency.

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
This paper proposes the use of a Gaussian window on the array factor as an interference mitigation method, aiming to avoid the computational complexity of the MVDR algorithm at the cost of a slight performance reduction. We show that by optimizing the parameters of the Gaussian window, it is possible to effectively mitigate the interfering signal if it is received within a certain angular range from the desired signal, while being still effective beyond that range. Finally, we show that the effectiveness of this approach is maintained across the full frequency reception range of the Ka-band, and confirm its validity using 8 × 8 and 16 × 16 array sizes. © 2022 IEEE.

2021

Wide Scanning Angle Millimetre Wave 1 x 4 Planar Antenna Array on InP at 300 GHz

Authors
Hussain, B; Salgado, HM; Pessoa, LM;

Publication
APPLIED SCIENCES-BASEL

Abstract
Featured Application Short-range millimetre wave communications. The design of a uniformly spaced 1 x 4 linear antenna array using epitaxial layers of benzocyclobutene over an InP substrate is demonstrated. The array elements are conjugately matched with a uni-travelling carrier photodiode at the input. The phased array is optimised to counteract mutual coupling effects by introducing metal strips with isolated ground planes for each radiating element. The proposed antenna array can provide a gain of 10 dBi with a gain variation of +/- 3 dB. The array operates over a bandwidth of 10 GHz (295-305 GHz) with a wide scanning angle of 100 degrees in the broadside.

Supervised
thesis

2022

Evaluating the Application of Time Series Forecasting with Confidence Intervals in IoT Self-Healing Systems

Author
Miguel Delgado Pinto

Institution
UP-FEUP

2022

High Power Efficiency, Wideband Microwave Power Amplifier Design Using Low-Cost Packaging and Integration Techniques for Emerging Transmitter Systems

Author
Hassan Safdary

Institution
UP-FEUP

2022

Constellation shaping in high-speed resilient underwater optical wireless communications

Author
João Henrique Melro Araújo - Feup

Institution
UP-FEUP

2022

Desenvolvimento de Uma Antena em Grafeno

Author
Luís Pedro Silva Ermida Martins de Freitas

Institution
UP-FEUP

2022

Efficiency and Financial Sustainability of Water Supply and Sanitation Services in Brazilian Municipalities

Author
Marco Tourinho Gama

Institution
UP-FEUP