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- Non-uniform microstrip antenna array for RX DSRC communicationsPublication . Varum, Tiago; Matos, João N.; Abreu, Ricardo; Pinho, PedroThe urgent need to mitigate traffic problems such as accidents, road hazards, pollution and traffic jam have strongly driven the development of vehicular communications. DSRC (Dedicated Short Range Communications) is the technology of choice in vehicular communications, enabling real time information exchange among vehicles V2V (Vehicle-to-Vehicle) and between vehicles and infrastructure V2I (Vehicle-Infrastructure). This paper presents a receiving antenna for a single lane DSRC control unit. The antenna is a non-uniform array with five microstrip patches. The obtained beam width, bandwidth and circular polarization quality, among other characteristics, are compatible with the DSRC standards, making this antenna suitable for this application. © 2014 IEEE.
- Low Profile Multi-Band Antenna for Mobile CommunicationsPublication . Calhau, Luis; Pinho, PedroIn this paper, the design of low profile antennas by using Electromagnetic Band Gap (EBG) structures is introduced. Taking advantage of the fact that they can behave as Perfect Magnetic Conductor (PMC), it is shown that these structures exhibit dual band in-phase reflection at WLAN (Wireless Local Area Network) bands, the 2.4 GHz and 5.2 GHz bands. These structures are applied to PIFA (Planar Inverted-F Antenna) and the results show that it is possible to obtain low profile PIFA's.
- UWB antenna for medical imagePublication . Cruz, Vítor; Matos, Joao; Pinho, Pedro; Pós-de-Mina Pato, MatildeMedical imaging based on different technologies is an essential tool in clinical practice, either to provide an accurate initial diagnosis or to monitoring diseases evolution. Microwave imaging technique has recently emerged as complementary method for breast imaging with high potential to become quite important for biomedical applications. This paper contributes to the technological development of this new technique, with the development of a broadband antenna (3 to 10 GHz) that operate in the range of the microwaves, which can be used for the detection of possible tumors, in particular, breast cancer. Also, some preliminary experience in a test bed is considered in order to detect possible differences between three samples which represent different situations: healthy breast, benign and malignant tumor breast.
- Electromagnetic simulation of amorphous silicon waveguidesPublication . Lourenço, Paulo; Fantoni, Alessandro; Pinho, PedroIn the past several decades, the Finite-Difference Time-Domain (FDTD) method has become one of the most powerful numerical techniques in solving the Maxwell’s curl equations and has been widely applied to solve complex optical and photonic problems. This method divides space and time into a regular grid and simulates the time evolution of Maxwell’s equations. This paper reports some results, obtained by a set of FDTD simulations, about the characteristics of amorphous silicon waveguides embedded in a SiO2 cladding. Light absorption dependence on the material properties and waveguide curvature radius are analysed for wavelengths in the infrared spectrum. Wavelength transmission efficiency is determined analysing the decay of the light power along the waveguides and the obtained results show that total losses should remain within acceptable limits when considering curvature radius as small as 3 μm at its most.
- Nonuniform broadband circularly polarized antenna array for vehicular communicationsPublication . Varum, Tiago; Matos, João N.; Pinho, Pedro; Abreu, RicardoRoad safety applications drive the development of vehicular communications as support to intelligent transport systems. The communications network necessary for this is supported by dedicated short-range communications (DSRC), which is based on roadside units (RSUs) and onbo ard units. In the RSU, the DSRC physical-layer standards, along with practical issues, require specific radiation patterns of the respective antenna, leading to the use of unusual arrays of antennas. This paper describes a new concept based on a binomial array structure, which simplifies the design of the antenna array while ensuring good performance. The new structure developed for this antenna enabled the design of a feed network using unbalanced power dividers in the same plane as that of the radiating elements, maintaining the favorable characteristics of microstrip antennas.
- 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.
- Smart environment technology as a possible enabler of smart citiesPublication . Gonçalves, Ricardo; Carvalho, Nuno Borges; Pinho, Pedro; Roselli, LucaThis paper discusses the technology of smart floors as a enabler of smart cities. The discussion will be based on technology that is embedded into the environment that enable location, navigation but also wireless power transmission for powering up elements siting on it, typically mobile devices. One of those examples is the smart floor, this implementation follows two paths, one where the floor is passive, and normally passive RFID's are embedded into the floor, they are used to provide intelligence into the surrounding space, this is normally complemented with a battery powered mobile unit that scans the floor for the sensors and communicates the information to a database which locates the mobile device in the environment. The other path for the smart city enabler is where the floor is active and delivers energy for the objects standing on top of it. In this paper these two approaches will be presented, by discussing the technology behind it. © 2014 IEEE.
- Dissipation factor and permittivity estimation of dielectric substrates using a single microstrip line measurementPublication . Gonçalves, Ricardo; Magueta, Roberto; Pinho, Pedro; Carvalho, NunoThe knowledge of the dielectric properties of materials, for the design of several components and circuits at high frequencies, is mandatory. In this paper, we present a simple method for the estimation of the dissipation factor (loss tangent) of dielectric materials based on the reflection measurement of a single microstrip line, which is applied to some common known materials, such as FR-4 and Rogers RO3010 laminates. The obtained results match well with the data on the literature for the considered materials.
- Evaluation of planar elliptical antenna array with inner counter-elliptical slotPublication . Pinho, Pedro; Carvalho, NunoThis paper presents and analyzes a low profile planar antenna array of elliptical elements with inner counter-elliptical slots. The antenna has single feed and provides two main directive radiation components (front and back), with gain higher than 7 dBi and circular polarization (CP) over the entire 5 GHz ISM& UNII bands. This approach also cancels the null over the elevation plane, which makes it suitable for bidirectional communications, also for proximity coverage. The inner slot of elliptical shape provides three additional degrees of freedom to match the planar monopole and/or array in impedance and polarization over the desired frequency band. An electromagnetic (EM) model of the proposed antenna is developed for numerical analysis and optimization. The principle of operation and parametric study of the antenna are provided. The antenna is fabricated and experimental results are presented. The number of elements in the array are chosen according to the desired gain and the inner elliptical slot parameters (major radius, elliptical ratio and rotation) scaled for impedance and polarization matching.
- Meander-line monopole antenna with compact ground plane for a bluetooth system-in-packagePublication . Santos, Hugo M.; Pinho, Pedro; Silva, Rui Pedro; Pinheiro, Márcio; Salgado, HenriqueIn this letter, a packaged compact meander-line monopole antenna for Bluetooth communications, manufactured in low-density fan-out technology, is presented. A combined size for the antenna and ground plane of 0.1 lambda(0) x 0.06 lambda(0) x 0.008 lambda(0) is obtained. Such small antennas are usually designed considering their connection to an evaluation board with a large ground plane, which improves their gain and bandwidth, but in this letter, the antenna is designed so it can work standalone without any further connection to printed circuit boards. The challenge of designing such a compact antenna is surpassed by performing a detailed modeling of the radiating meander-line element altogether with its finite ground plane, a tuning inductor, and an inductive coupling feed. The antenna model is developed in Ansys HFSS using the finite element method, which is later validated experimentally. Measurements of the return loss radiation pattern are carried out, and final results show a -6 dB bandwidth of approximately 110 MHz and a gain of -8.7 dBi, at 2.42 GHz.