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- 3D antenna characterization for WPT applicationsPublication . Jordão, Marina; Pires, Diogo; Belo, Daniel; Pinho, Pedro; Carvalho, Nuno BorgesThe main goal of this paper is to present a three-dimensional (3D) antenna array to improve the performance of wireless power transmission (WPT) systems, as well as its characterization with over-the-air (OTA) multi-sine techniques. The 3D antenna consists of 15 antenna elements attached to an alternative 3D structure, allowing energy to be transmitted to all azimuth directions at different elevation angles without moving. The OTA multi-sine characterization technique was first utilized to identify issues in antenna arrays. However, in this work, the technique is used to identify which elements of the 3D antenna should operate to transmit the energy in a specific direction. Besides, the 3D antenna design description and its characterization are performed to authenticate its operation. Since 3D antennas are an advantage in WPT applications, the antenna is evaluated in a real WPT scenario to power an RF-DC converter, and experimental results are presented.
- Challenges in resource-constrained IoT devices: energy and communication as critical success factors for future IoT deploymentPublication . Pereira, Felisberto; Correia, Ricardo; Pinho, Pedro; Lopes, Sérgio I.; Carvalho, Nuno BorgesInternet of Things (IoT) has been developing to become a free exchange of useful information between multiple real-world devices. Already spread all over the world in the most varied forms and applications, IoT devices need to overcome a series of challenges to respond to the new requirements and demands. The main focus of this manuscript is to establish good practices for the design of IoT devices (i.e., smart devices) with a focus on two main design challenges: power and connectivity. It groups IoT devices in passive, semi-passive, and active, giving details on multiple research topics. Backscatter communication, Wireless Power Transfer (WPT), Energy Harvesting (EH), chipless devices, Simultaneous Wireless Information and Power Transfer (SWIPT), and Wake-Up Radio (WUR) are some examples of the technologies that will be explored in this work.
- When backscatter communication meets vehicular networks: boosting crosswalk awarenessPublication . Pereira, Felisberto; Sampaio, Hugo; Chaves, Ricardo; Correia, Ricardo; Luís, Miguel; Sargento, Susana; Jordão, Marina; Almeida, Luís; Senna, Carlos; Oliveira, Arnaldo S. R.; Carvalho, Nuno BorgesThe research of safety applications in vehicular networks has been a popular research topic in an effort to reduce the number of road victims. Advances on vehicular communications are facilitating information sharing through real time communications, critical for the development of driving assistance systems. However, the communication by itself is not enough to reach the most desired target as we need to know which safety-related information should be disseminated. In this work, we bring passive sensors and backscatter communication to the vehicular network world. The idea is to increase the driver (or vehicle) awareness regarding the presence of pedestrians in a crosswalk. Passive sensors and backscatter communication technologies are used for the pedestrians’ detection phase, while the vehicular network is used during the dissemination of the detection information to surrounding vehicles. The proposed solution was validated through end-to-end experimentation, with real hardware and in a real crosswalk with real pedestrians and vehicles, demonstrating its applicability.
- RFID Tattoo for COVID-19 Temperature MeasuringPublication . Silveira, Tagleorge; Pinho, Pedro; Carvalho, Nuno BorgesIn order to assist in the screening and monitoring of possible infected by COVID-19, whose fever is one of the initial symptoms, a RFID tattoo tag for human monitoring was developed. The prototype of the tattoo tag presented proved to be effective in measuring human body temperature from 36° to 40° C, thus being a viable option for large-scale screening and analysis, and for being made with aluminum foil and school adhesive tape. That when using these materials, it presents itself as a disposable device, of low cost, durable, and operable in the RFID UHF frequency range.
- A review of antenas for indoor positioning systemsPublication . Brás, Luís; Carvalho, Nuno Borges; Pinho, Pedro; Kulas, Lukasz; Nyka, KrzysztofThis paper provides a review of antennas applied for indoor positioning or localization systems. The desired requirements of those antennas when integrated in anchor nodes (reference nodes) are discussed, according to different localization techniques and their performance. The described antennas will be subdivided into the following sections according to the nature of measurements: received signal strength (RSS), time of flight (ToF), and direction of arrival (DoA). This paper intends to provide a useful guide for antenna designers who are interested in developing suitable antennas for indoor localization systems.