Browsing by Author "Gonçalves, Ricardo"
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- 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.
- 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.
- Compact, frequency reconfigurable, printed monopole antennaPublication . Gonçalves, Ricardo; Pinho, Pedro; Carvalho, Nuno B.This paper proposes a possible implementation of a compact printed monopole antenna, useful to operate in UMTS and WLAN bands. In order to accomplish that, a miniaturization technique based on the application of chip inductors is used in conjunction with frequency reconfiguration capability. The chip inductors change the impedance response of the monopole, allowing to reduce the resonant frequency. In order to be able to operate the antenna in these two different frequencies, an antenna reconfiguration technique based on PIN diodes is applied. This procedure allows the change of the active form of the antenna leading to a shift in the resonant frequency. The prototype measurements show good agreement with the simulation results.
- Corrugated horn antenna for a CosmoGal satellite with reduced dimensionsPublication . Soares, Pedro; Pinho, Pedro; Gonçalves, RicardoThis paper presents the design methodology for the creation of corrugated horn antennas for the CosmoGal satellite. The mission will collect the radiation of the cosmic microwave background, by a radiometer in three different radio astronomy frequency bands (10.6-10.7GHz; 15.35-15.4GHz; 23.6-24GHz). It is discussed the design of several types of horns, simulated with the CST software. The best result points to a choked Gaussian corrugated horn antenna, with directivity of 23 dBi, side lobes 35 dB below and cross polarization better than -45 dB. Plus, with the advantage of having a small dimension, with a total length of only 7.43λ © 2014 IEEE.
- Design and evaluation of multi-band RF energy harvesting circuits and antennas for WSNsPublication . Borges, Luís M.; Barroca, Norberto; Saraiva, Henrique M.; Tavares, Jorge; Gouveia, Paulo T.; Velez, Fernando J.; Loss, Caroline; Salvado, Rita; Pinho, Pedro; Gonçalves, Ricardo; Carvalho, Nuno Borges; Chavez-Santiago, Raúl; Balasingham, IlangkoRadio frequency (RF) energy harvesting is an emerging technology that will enable to drive the next generation of wireless sensor networks (WSNs) without the need of using batteries. In this paper, we present RF energy harvesting circuits specifically developed for GSM bands (900/1800) and a wearable dual-band antenna suitable for possible implementation within clothes for body worn applications. Besides, we address the development and experimental characterization of three different prototypes of a five-stage Dickson voltage multiplier (with match impedance circuit) responsible for harvesting the RF energy. Different printed circuit board (PCB) fabrication techniques to produce the prototypes result in different values of conversion efficiency. Therefore, we conclude that if the PCB fabrication is achieved by means of a rigorous control in the photo-positive method and chemical bath procedure applied to the PCB it allows for attaining better values for the conversion efficiency. All three prototypes (1, 2 and 3) can power supply the IRIS sensor node for RF received powers of -4 dBm, -6 dBm and -5 dBm, and conversion efficiencies of 20, 32 and 26%, respectively. © 2014 IEEE.
- 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 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.
- Development of a textile antenna using a continuous substrate integrating the ground planePublication . Loss, Caroline; Salvado, Rita; Gonçalves, Ricardo; Pinho, PedroThe exponential growth in the wearable market is boosting the industrialization process of manufacturing textile antennas. The patch of the printed antennas can be easily cut, embroidered or screen printed by machines. The conception of an optimal industrial substrate that meets all the mechanical and electromagnetic requirements is still a challenge. This paper presents a printed textile antenna for ISM band using a continuous Substrate Integrating the Ground Plane (SIGP). The SIGP is a novel textile material, which is a double fabric that integrates the dielectric substrate and the conductive ground plane in a single textile.
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