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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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Details

004
Publications

2018

Elliptical Monopole Antenna on InP Substrate for Sub-THz RTD-based Oscillators

Authors
Santos, HM; Pessoa, LM; Salgado, HM; Pinho, P;

Publication
2018 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETING

Abstract
The high permittivity of InP substrates has been a limiting factor for the bandwidth and efficiency of antennas fabricated in this material. In this manuscript we propose an elliptical monopole, monolithically fabricated in InP, fed by a CPW line. The suggested topology was simulated using HFSS finite element method. Input reflection coefficient measurements were performed on the monopole to validate the proposed antenna. Simulated and measured -10 dB bandwidths of 27 and 24 GHz were obtained, respectively. The peak simulated efficiency and realized gain were 95.37% and 4.6 dBi.

2018

Low-Density Fan-Out SiP for Wearables and IoT with Heterogeneous Integration

Authors
Martins, A; Pinheiro, M; Ferreira, AF; Almeida, R; Matos, F; Oliveira, J; O'Toole, E; Santos, HM; Monteiro, MC; Gamboa, H; Silva, RP;

Publication
2018 INTERNATIONAL WAFER LEVEL PACKAGING CONFERENCE (IWLPC)

Abstract
The development of Low-Density Fan-Out (LDFO), formerly Wafer Level Fan-Out (WLFO), platforms to encompass the requirements of potential new markets and applications such as the Internet of Things (IoT) is crucial to maintain LDFO as the leading Fan-Out technology. This drives the development of a new set of capabilities in the current standard LDFO process flow to break through the existing technology boundaries. One of the most widely discussed advantages of LDFO packaging is heterogeneous high-density system integration in a package. LDFO System in Package (LDFO SiP) integrates active dies, passive components and even already-packaged components using other packaging technologies. This heterogeneous integration is based on a wide range of different geometries and materials placed inside the LDFOSiP with high accuracy. Ultimately, heterogeneous integration will be fundamental to achieve new levels of miniaturization. However, multi-die solutions face several challenges such as bare-die availability, passives integration, antenna integration, low power budget, test complexity and reliability. Package research and development (R&D) must overcome all of these issues to build a product with high volume manufacturability. The wafer level SiP (WLSiP) technology required to enable the new features and processes needs to be ready for high volume manufacturing of new products at high yield and reasonable cost. This paper presents the approaches used to effectively enable LDFO SiPs (WLSiPs): 1. A pre-formed vias solution is employed to connect front to back side of the package, including development for high accuracy via bar placement. 2. A wafer front-side to back-side redistribution layer (RDL) alignment solution was developed. 3. Space requirement reduction between components to achieve the smallest possible package. 4. Miniaturized Bluetooth antenna integration in the RDL. 5. Creation of a stacking concept (vertical connections to create a modular system that enables easy addition of new features to the final product). Inside the package (excluding the area reserved for the antenna), components are densely packed: several sensors, power management components, radio communication and all required passives are incorporated into a single WLSiP. Connecting all these features to create a component that works by connecting only a single battery required implementing a double sided, multi-layer RDL, while maintaining the ability to create a 3D solution by stacking vertical connections for several other solutions. The result is an approach that easily adapts the system to a variety of customers' needs. The work done is part of the collaborative COMPETE2020-PT2020 funding program under "IoTiP-Internet of Thing in Package" project no 017763, Projetos de I&DT Empresas em CoPromocao.

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.