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About

Hugo Santos obtained his MSc degree in FEUP, specializing in communication technologies. He is a MAP-Tele PhD student and researcher in the OET (Optical and Electronic Technologies) group of CTM. His main interests include, among others, RF and microwave engineering, electrically small antennas, on-package and on-chip antennas for mm-Wave, antenna arrays and wireless power transmission.

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Publications

2016

Antenna Design for Underwater Radio Communications

Authors
Inacio, SI; Pereira, MR; Santos, HM; Pessoa, LM; Teixeira, FB; Lopes, MJ; Aboderin, O; Salgado, HM;

Publication
OCEANS 2016 - SHANGHAI

Abstract
In this paper we assess the influence of the conductivity of the medium on the radiation characteristics and input impedance of a loop antenna designed for underwater communications. The initial study is based on simulation of the antenna characteristics using FEKO electromagnetic (EM) software. Additionally, an equivalent circuit model of the antenna is also obtained and simulation of the input impedance on ADS software shows good agreement with the EM simulator. It is found that the radiation pattern, of the loop antenna changes significantly with the conductivity of the medium, from freshwater to seawater. The loop antennas were built with baluns and tested in freshwater, where the insertion loss between two identical antennas and the radiation pattern of one of them were also measured. The results show good agreement with the simulations.

2016

Assessment of design trade-offs for wireless power transfer on seawater

Authors
Santos, HM; Pereira, MR; Pessoa, LM; Duarte, C; Salgado, HM;

Publication
OCEANS 2016 MTS/IEEE Monterey, OCE 2016

Abstract
In this work we propose a method for maximization of the efficiency of an underwater wireless power transfer system that has to cope with load changes, quality factor and coupling coefficient deviations. By means of 3D electromagnetic simulation and numerical computation, parameter analysis is accomplished using different compensation methods, namely series-series, series-parallel and parallel-parallel. Moreover, a linear load profile is assessed as a proof of concept applicable to more complex load behaviours. For this linear load variation a maximum measured average efficiency of 82% was obtained throughout the entire battery state of charge. Electronics and full system considerations are also presented. Finally, a good agreement between theoretical predictions of the proposed method, simulation assessment and measurement results was verified. © 2016 IEEE.

2016

Dipole Antenna for Underwater Radio Communications

Authors
Inacio, SI; Pereira, MR; Santos, HM; Pessoa, LM; Teixeira, FB; Lopes, MJ; Aboderin, O; Salgado, HM;

Publication
2016 IEEE THIRD UNDERWATER COMMUNICATIONS AND NETWORKING CONFERENCE (UCOMMS)

Abstract
The radiation characteristics of a dipole antenna when immersed in both fresh and seawater are assessed through simulation and experimental work. Simulations show that the antenna's bandwidth and radiation pattern change with the properties of the medium where it is placed, namely the conductivity of the medium. Two dipoles antennas with current baluns were built and tested experimentally in freshwater. The tests included the measurement of the insertion loss between two identical dipole antennas and their radiation pattern. The results obtained show a good agreement between the simulation and experimental results.

2016

Analysis of J-Pole antenna configurations for underwater communications

Authors
Aboderin, O; Inacio, SI; Santos, HM; Pereira, MR; Pessoa, LM; Salgado, HM;

Publication
OCEANS 2016 MTS/IEEE Monterey, OCE 2016

Abstract
The capability of relatively high-speed short-range communications of Autonomous Underwater Vehicles (AUVs) in underwater scenarios, for example, for communication between vehicles or when the AUV is approaching a docking station for downloading of data gathered during a survey mission, is becoming a relevant application in the context of sea exploration and mining. In this paper the analysis of the J-pole antenna and two of its configurations namely Super J-pole and Collinear J-pole antennas are presented, aimed at improving the propagation distance and data rates when such antennas are installed on AUV for onward usage in underwater communications. The performance of these three antennas is assessed through simulation in fresh and sea water, operating in the High Frequency (HF) band. These antennas are compared in terms of bandwidth and directivity which are important elements in the transmission and reception of electromagnetic signals. The results obtained show that these antennas will be desirable both for improved data rates and propagation distance in fresh and sea water. The antennas were designed with FEKO electromagnetic simulation software. © 2016 IEEE.

2016

Simulation and Experimental Evaluation of a Resonant Magnetic Wireless Power Transfer System for Seawater Operation

Authors
Pereira, MR; Santos, HM; Pessoa, LM; Salgado, HM;

Publication
OCEANS 2016 - SHANGHAI

Abstract
The use of high efficiency resonant coupling wireless power systems for subsea operations is here considered for the charging of autonomous underwater vehicles. In this paper, two architectures based on two different inductors are analysed for their potential as resonant wireless power couplers. Both systems were designed and optimised through electromagnetic 3D simulations, upon which two prototypes were constructed and measured. Efficiencies as high as 75% for distances up to 5 cm were achieved on experimental testing.