105 documents found, page 1 of 11
Best practices for accurate results using numerical solvers for microwave body ...
Martins, R. A.; Godinho, D.; Felício, J. M.; Savazzi, M.; Costa, J. R.; Conceição, R.; Fernandes, C. A.In this paper, we indicate best practices that should be observed when using numerical solvers for microwave body sensing. We show the impact of not minding these aspects in the case of microwave breast scanning, using the Computer Simulation Technology software tool. To this end we simulate a homogeneous breast with a 5-mm radius spherical tumor placed inside. The breast is illuminated by a broadband antenna t...
Antenna position layout and frequency impact on tumor detection in microwave br...
Martins, R. A.; Felício, J.; Costa, J. R.; Fernandes, C. A.We present a systematic study in which we assess the antenna position layout and frequency point distribution of a MWI system, that can potentially improve tumor detection and minimize acquisition time. To this end, we performed measurements on a dry MW setup, using a slot-based antenna in the [2]–[5] GHz frequency range to scan an anthropomorphic breast phantom, with two different tumor positions, for 40 angul...
Assessing the detection of floating plastic litter with advanced remote sensing...
de Fockert, A.; Eleveld, M. A.; Bakker, W.; Felício, J. M.; Costa, T. S.; Vala, M.; Marques, P.; Leonor, N.; Moreira, A.; Costa, J. R.Remote sensing technologies have the potential to support monitoring of floating plastic litter in aquatic environments. An experimental campaign was carried out in a large-scale hydrodynamic test facility to explore the detectability of floating plastics in ocean waves, comparing and contrasting different microwave and optical remote sensing technologies. The extensive experiments revealed that detection of pl...
Revisiting Risley prism transmit-array antennas using a novel co-design phase c...
Matos, S. A.; Fonseca, N. J. G.; Serra, J.; Felício, J. M.; Costa, J. R.; Femandes, C.Mechanical beam steering using two independent axially rotating metasurfaces (Risley Prism configuration) have proved to be a cost-effective solution for millimeter wave (mmW) antennas. Adapting this canonical beam steering concept from optics to mmW using metasurfaces (instead of wedge prisms) allows achieving a greater design flexibility. Many works have explored different ways of encoding the required phase ...
On the feasibility of using Passive mm-Wave Imaging for marine litter detection...
Vala, M.; Felício, J. M.; Costa, T. S. da.; Leonor, N.; Costa, J. R.; Marques, P.; Moreira, A. A.; Matos, S. A.; Caldeirinha, R. F. S.; Fernandes, C. A.Large research effort is appearing in the literature on remote detection of plastic marine litter, using optical instruments, and lately microwaves. We present here a feasibility study of passive mm-wave imaging (PMMWI) for the same goal. Several measurements were taken in a controlled pool environment both in static and agitated water conditions using a W-band radiometer to assess the influence of plastic on t...
Validation of a compact microwave imaging system for bone fracture detection
Santos, K. C.; Fernandes, C. A.; Costa, J. R.This work presents a systematic evaluation of the effectiveness of an air-operated microwave imaging (MWI) system for detection of arbitrarily oriented thin fractures in superficial bones, like the tibia. This includes the proposal of a new compact, portable setup where a single Vivaldi antenna performs a semi-cylindrical scan of the limb. The antenna is operated in monostatic radar mode, near the skin but with...
Achieving wide-angle mechanical beam steering in Ka-band with low-profile trans...
Matos, S.; Vaquero, Á. F.; Arrebola, M.; Costa, J. R.; Felício, J.; Fernandes, C.; Fonseca, N. J. G.Beam scanning and high gain are fundamental requisites for antennas operating at millimeter wave, where many 5G and satellite-on-the-move applications are emerging. Mechanical beam steering using Transmit-arrays (TAs) has been proposed as a viable alternative to the more costly and complex electronic-based solutions. As a spatially fed array, TAs operate with a minimal focal length, distance between the primary...
Detection of low permittivity floating plastic sheets at microwave frequencies
Costa, T. S. da.; Felício, J. M.; Vala, M.; Leonor, N.; Costa, J. R.; Marques, P.; Moreira, A. A.; Caldeirinha, R.; Matos, S. A.; Fernandes, C. A.Microwaves are surfacing in remote sensing as a viable or complementary technology to optical techniques for the detection and monitoring of floating plastic litter, given their advantages in, e.g., earth observation missions. There is a limited number of studies that analyze the detection of low permittivity plastics in a systematic manner. To contribute to this topic, we evaluated the microwave response of a ...
Dielectric versus patch-based implementations of Risley Prism transmit-arrays i...
Matos, S.; Felício, J.; Costa, J. R.; Fernandes, C. A.; Fonseca, N.Many millimeter wave applications related with 5G and Satellite on the move (SoTM) communications rely on cost-effective high-gain antennas with wide beam scanning. Mechanical steering solutions can reduce the complexity and cost of the fully-electronic beam steering counterpart (e.g. phased arrays). Mechanical scanning with Transmit-array (TA) antennas can provide a balanced compromise between cost, size, and ...
Design of low-profile transmitarray antennas with wide mechanical beam steering...
Vaquero, Á. F.; Teixeira, J.; Matos, S. A.; Arrebola, M.; Costa, J. R.; Felício, J. M.; Fernandes, C. A.; Fonseca, N. J. G.Mechanical beam steering using a single Transmitarray (TA) can be a cost-effective solution for a high-gain antenna with wide-angle scanning. Elevation scanning can be achieved by a linear displacement of the feed in the focal plane parallel to the aperture of diameter D. When designing compact terminals with a short focal length F and with high gain, the aberrations caused by this mechanical movement become th...