Percorrer por autor "Carvalho, Nuno"
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- 3D antenna array for SWIPT Sensing with WPT capabilitiesPublication . Pires, Diogo; Belo, Daniel; Jordão, Marina; Pinho, Pedro; Carvalho, NunoIn this work, the design and development of an alternative three-dimensional array is presented. This arrangement aims to improve Simultaneously Wireless Information and Power Transfer (SWIPT) systems and to provide advantages when integrated into a Wireless Sensor Network (WSN) architecture. The conceived 3D antenna array consists of eight antenna elements operating at 5.65 GHz that are attached in a 3D printed heptagonal prism. With this structure, it is intended to achieve as close as possible to an omnidirectional radiation pattern with considerable gain, avoiding power losses. The experimental measurements carried out are in line with the performed electromagnetic simulations and validate the array operation. A full azimuth coverage was ensured with an average realized gain of 6.7 dBi. For some azimuth directions, this gain can reach approximately 8.35 dBi. This array proves to be a reliable solution to fed multiple low-power sensors that are placed over the 360 azimuth angles.
- 3D antenna for wireless power transmission aperture coupled microstrip antenna with dielectric lensPublication . Dias, Gonçalo; Pinho, Pedro; Gonçalves, Ricardo; Carvalho, NunoNowadays 3D printers are useful for the development and rapid prototyping of dielectric structures for radiation manipulation and support of antennas. This is possible since the materials used in this machines are essentially dielectric. These can be used as radiating elements (dielectric resonators), as radiation handlers (lenses) or as a supporting base for applying conductive material to radiation (substrates). In this paper we explore 3D printing technology to develop a lens antenna for wireless power transfer operating at 20 GHz. The design, simulation and measurement of an aperture coupled microstrip antenna with dielectric lens is presented and discussed. The lens is used to focus the beam of lower gain feed antenna to produce a highly directive pattern with low side lobe.
- 3D printed lens antenna for wireless power transfer at Ku-bandPublication . Gonçalves, Ricardo; Pinho, Pedro; Carvalho, NunoIn this paper we present the design of an antenna, operating in the Ku-band, conceived for wireless power transfer systems. It comprises an hemispherical dielectric lens, fabricated using 3D printing technology, fed by a microstrip patch antenna array. The conjugation of the dielectric lens with the microstrip patch array allows the development of a compact high gain antenna. The antenna presents a matched bandwidth between 12.7 and 13.15 GHz and a maximum gain of 18.1 dBi at each element.
- 5.8 GHz Microstrip antennas and array for microwave power transferPublication . Carvalho, António; Carvalho, Nuno; Pinho, Pedro; Georgiadis, Apostolos; Constanzo, AlessandraWireless power transmission presents itself as being a solution to some common problems of the extensive use of electronic devices such as the removal of parasitic components present in feeding pads and the constant charge of electronic devices without the need of wires. This solution becomes attractive, for example, as a means of increasing the flight time of battery dependent unmanned aerial vehicles. Microstrip antenna due to their ease of manufacturing, low fabrication cost, support of different polarizations and conformability to irregular surfaces and different substrates, seem very advantageous in being used for microwave power transmission. This paper presents a linearly polarized 16-element antenna array with uniform amplitude and phase excitation proposed for power transmission while both a linearly and circularly polarized single element patch are proposed for reception.
- Antenna design for ultra-compact Bluetooth devicesPublication . Pereira, Felisberto; Pinho, Pedro; Gonçalves, Ricardo; Carvalho, Nuno; Lobato, João; Lopes, Sérgio I.This paper presents a solution for an ultra-compact antenna for small Bluetooth devices. The work considers the battery and the electronic components influence in the antenna design process for a real device, i.e. a Bluetooth tracker. Three different models for representing the battery and the main electronic components are studied: (i) a simple model that represents both battery and components by a ground plane; (ii) a model that represents the battery realistically and the components by a ground plane and (iii) a model that represents realistically both battery and components.
- Beam steering antenna and network design for WPT applicationsPublication . Costa, Andreia; Gonçalves, Ricardo; Pinho, Pedro; Carvalho, NunoThe Internet of Things (IoT) is increasingly present in our daily routine. It allows to use technology in a more efficient way. Important enabler of it is Wireless Power Transmission (WPT) as an alternative to electrical conductors (wires and cables). Given these aspects a linear microstrip antenna array was developed for 2.45 GHz ISM band, with Circular Polarization (CP). The main objective of this array is to create a beam to power up wireless sensors within a specific area of a room. The steering performance of the antenna is simulated using CST tool. Simulation results are found to be in good agreement with measurements.
- Characterization of Th2 serum immune response in acute appendicitisPublication . Carvalho, Nuno; Almeida, Jani-Sofia; Carolino, Elisabete; Lopes, Francisco; Henriques, Susana; Vaz, João; Coelho, Hélder; Santos, Paulo Rodrigues; Rosa, Manuel Santos; Moita, Luís; Luz, Carlos; Costa, Paulo MatosAcute Appendicitis (AA) is the commonest abdominal digestive surgical emergency, but its etiology is not clarified. Based on histologic observations, an allergic cause has been proposed. In a type I hypersensitivity allergic reaction, there is a Th2 immune response characterized by Th2 cells, eosinophils, basophils, IgE, IL-4, IL-5, and IL-13 serum elevation. Recent studies showed a local appendicular endoluminal and parietal Th2 immune response in acute phlegmonous appendicitis. We performed a prospective single-center study where we evaluated the Th2 blood immune response in 38 patients with acute phlegmonous appendicitis, 27 patients with acute gangrenous appendicitis, and 18 patients with the clinical picture of AA, who underwent appendectomy but had negative histology for AA (negative appendectomy group). Higher levels of basophils were found in phlegmonous appendicitis (p = 0.03), and higher levels of eosinophils were found in the control group (p = 0.003). Effector memory CD4 T cells re-expressing CD45RA were higher in gangrenous (p = 0.020) and central memory CD4 T cells in phlegmonous appendicitis (p = 0.004). The number of Th2 circulating cells was higher in gangrenous appendicitis (p = 0.037), while Th1 circulating cells were higher in phlegmonous appendicitis (p = 0.028). IL-4 blood concentrations were elevated in acute gangrenous appendicitis (p = 0.029). No significant differences were found in the levels of IgE, IL-5, or IL-13 in any of the groups. Thus, a Th2 response was not detected in patients’ serum with phlegmonous appendicitis. Serum levels of IgE, IL-5, and IL-13 were not different among patients with acute phlegmonous appendicitis, acute gangrenous appendicitis, and the negative appendectomy group. These findings are in contrast to our previous work in which we evaluated the Th2 response at the local level, at the appendicular luminal aspect and appendicular wall, in phlegmonous appendicitis and control groups, and we unequivocally showed a Th2 response in phlegmonous appendicitis. Thus, in patients with phlegmonous appendicitis, the local Th2 response is not reflected in the serum levels of immune cells and cytokines.
- Design and implementation of a 3D printed discone antenna for TV broadcasting systemPublication . Gonçalves, Ricardo; Pinho, Pedro; Carvalho, NunoDiscone antennas are wide bandwidth and omnidirectional radiation antennas that are widely used in VHF and UHF broadcasting systems. This paper presents the design and implementation of a discone antenna, for indoor use in a digital TV receiving/transmitting system, which was developed using 3D printing technology, allowing the development to be simple, quick and less expensive. The antenna presents a measured matched bandwidth, below - 10dB of return loss, between 380 MHz and 3 GHz. Simulation and measurements match, with the antenna presenting an omnidirectional radiation pattern within the considered TV band.
- Design of an efficient D-TV energy harvesting system for low-power applicationsPublication . Moura, Tiago; Carvalho, Nuno; Pinho, PedroCollect energy from the surroundings is being biased to power-up devices in order to turn them self-sustainable. On the other hand, the spectrum resultant from the telecommunications tends to progressively increase and becomes wide-reaching, constituting an enormous opportunity to energy harvesting. This work aims to contribute with useful trends into the rectifier design to fulfil energy harvesting purposes. Three rectifiers are designed to collect D-TV spectrum and optimized to operate at low input power conditions. Measurements indicates 63% efficiency at -10.5 dBm input power with the Portuguese D-TV signal.
- Design of UAV and ground station antenas for communications link budget improvementPublication . Costa, Andreia; Gonçalves, Ricardo; Pinho, Pedro; Carvalho, NunoThis paper presents the design and implementation of two antennas aiming the improvement of the link budget between an Unmanned Aerial Vehicle (UAV) and the ground station. The performance of the antennas is simulated using CST software tool and the simulation results are found to be in good agreement with the measurements. The UAV antenna presents 6 dBi of gain with an omni-directional coverage. The ground station antenna is a directional antenna based on a stacked configuration allowing an increase of the bandwidth while achieving a gain of 13.5 dBi. Both antennas operate at 1.335 GHz and a range of 50 Km is predicted when included in the communication system.
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