Details
Name
Sofia Isabel InácioRole
Research AssistantSince
15th September 2015
Nationality
PortugalCentre
Telecommunications and MultimediaContacts
+351222094299
sofia.i.inacio@inesctec.pt
2024
Authors
Inácio, SI; Pessoa, LM;
Publication
18th European Conference on Antennas and Propagation, EuCAP 2024
Abstract
This paper presents a 1-bit graphene-based reflective reconfigurable intelligent surface (RIS), namely a reflectarray antenna, that operates in the Ka-band (27-31 GHz). The reflectarray unit-cell features a simple structure with one metal layer, a Rogers RT5880 substrate and a Graphene Sandwich Structure (GSS) on top. The GSS comprises two layers of graphene separated by a diaphragm paper and a thin PVC layer to enhance its durability. The reflectarray can ensure a 1-bit phase shift resolution, by alternating the bias voltage applied to the graphene. The unit-cell simulation shows that the losses are around 3 dB over the studied band for both unit-cell states. An equivalent circuit model is presented to facilitate the analysis and design of GSS-based unit-cells. The full-wave simulation results of a 32×32 reflectarray indicate a gain of 25 dBi for a steering angle of 10 deg., displaying a 1 dB gain bandwidth of 15%, confirming the promise of the graphene-based radiating elements. © 2024 18th European Conference on Antennas and Propagation, EuCAP 2024. All Rights Reserved.
2024
Authors
Inácio, SI; Pessoa, LM;
Publication
2024 4TH URSI ATLANTIC RADIO SCIENCE MEETING, AT-RASC 2024
Abstract
This paper presents an optically transparent 2-bit unit-cell for reflective intelligent surface applications in Wi-Fi 6E. The unit-cell is based on a metalmesh and can be reconfigured electronically by adjusting the voltage applied to a varactor diode. The performance of the RIS is demonstrated through simulation, which shows that the results are in good agreement with the theoretical predictions.
2024
Authors
Inácio, SI; Pessoa, LM;
Publication
2024 18TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP
Abstract
This paper presents a 1-bit graphene-based reflective reconfigurable intelligent surface (RIS), namely a reflectarray antenna, that operates in the Ka-band (27 - 31 GHz). The reflectarray unit-cell features a simple structure with one metal layer, a Rogers RT5880 substrate and a Graphene Sandwich Structure (GSS) on top. The GSS comprises two layers of graphene separated by a diaphragm paper and a thin PVC layer to enhance its durability. The reflectarray can ensure a 1-bit phase shift resolution, by alternating the bias voltage applied to the graphene. The unit-cell simulation shows that the losses are around 3 dB over the studied band for both unit-cell states. An equivalent circuit model is presented to facilitate the analysis and design of GSS-based unit-cells. The full-wave simulation results of a 32x32 reflectarray indicate a gain of 25 dBi for a steering angle of 10 deg., displaying a 1 dB gain bandwidth of 15%, confirming the promise of the graphene-based radiating elements.
2016
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
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.
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