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Zhang, H. (author)In recent decades, dielectric lens antennas have been more and more adopted and developed for sensing and imaging applications at sub-millimeter (sub-mm) wavelengths because they can achieve high gain while keeping their physical size and weight acceptable at these wavelengths. More recently, as low-loss and low-cost lens materials have become...doctoral thesis 2024
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Mohammadkarimi, M. (author), Leus, G.J.T. (author), Rajan, R.T. (author)A new method for joint ranging and Phase Offset (PO) estimation of multiple drones/aircrafts is proposed in this paper. The proposed method employs the superimposed uncoordinated Automatic Dependent Surveillance-Broadcast (ADS-B) packets broadcasted by drones/aircrafts for joint range and PO estimation. It jointly estimates range and PO prior...journal article 2024
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Ozzola, R. (author), Neto, A. (author), Imberg, Ulrik (author), Cavallo, D. (author)We present a dual-polarized connected array of slots with an artificial dielectric layer (ADL) radome for mobile communication applications operating in the sub-6 GHz and the upper 6 GHz bands of 5G. The radiating slots are combined with two interchangeable ADL radomes with different thicknesses, targeting the bands 6-8 and 2-8 GHz,...journal article 2024
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Stumpf, Martin (author), Antonini, Giulio (author), Lager, I.E. (author)The transient electromagnetic (EM) excitation of a narrow slot in a perfectly electrically conducting (PEC) screen that separates two homogeneous dielectric halfspaces, a simplified model of a typical feeding structure of leaky lens antennas, is analyzed numerically in the time domain (TD). The problem is formulated using the TD reciprocity...journal article 2024
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Gu, Junhong (author), Stumpf, Martin (author), Neto, A. (author), Lager, I.E. (author)A strictly causal numerical study of the pulsed operation of a weakly dispersive, leaky wave (LW) antenna is presented. The intricacies at the forefront of the electromagnetic (EM) field radiated from a gap-fed slot in a perfectly electrically conducting (PEC) sheet are evidenced for the first time. The radical effect of a free-space gap...journal article 2024
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Hu, Weiya (author), Coco Martin, C.M. (author), Cavallo, D. (author)A semi-analytical method is presented for the design of gradient index (GRIN) flat lenses. Closed-form expressions are derived to define the refractive index distribution of the lens, for several cases: collimating lenses with on-axis feed, collimating lenses with off-axis feed, lenses converting spherical wavefronts with different...journal article 2024
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Hernandez-Burgos, Sergi (author), Gibert, Ferran (author), Broquetas, Antoni (author), Kleinherenbrink, M. (author), De la Cruz, Adrian Flores (author), Gomez-Olive, Adria (author), Garcia-Mondejar, Albert (author), Aparici, Monica Roca i. (author)The 2-D frequency-based omega-K method is known to be a suitable algorithm for fully focused SAR (FF-SAR) radar altimeter processors, as its computational efficiency is much higher than equivalent time-based alternatives without much performance degradation. In this article, we provide a closed-form description of a 2-D frequency-domain omega...journal article 2024
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Wang, Ranran (author), Zhang, Jun (author), Lu, Yijun (author), Ren, S. (author), Huang, Jiandong (author)The design of geopolymer concrete must meet more stringent requirements for the landscape, so understanding and designing geopolymer concrete with a higher compressive strength challenging. In the performance prediction of geopolymer concrete compressive strength, machine learning models have the advantage of being more accurate and faster....journal article 2024
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Locatelli, A. (author), Alvarez-Perez, Jose Luis (author), Yarovoy, Alexander (author)Multi-path propagation over asphalt road surfaces at automotive radar frequencies is studied. A new expression for the reflection coefficient from asphalt which takes into account asphalt surface roughness is proposed. The classic two-ray method to take into account the multi-path is improved using antenna radiation patterns and the antenna tilt...conference paper 2024
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Aslan, Y. (author), Roederer, A.G. (author), Fonseca, Nelson J.G. (author), Angeletti, Piero (author), Yarovoy, Alexander (author)An innovative reconfigurable beamforming network concept for multiple high-gain agile and mutually zero-forced beam generation is proposed. Four-port couplers and variable phase shifters are used to synthesize the network. A 2 beam by 7 element beam former is designed and fabricated as proof of concept. A static scenario with the two beams...conference paper 2024
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Hehenberger, S.P. (author), Caizzone, Stefano (author), Yarovoy, Alexander (author)The utilization of low-cost hybrid additive manufacturing equipment for creating a fully integrated patch antenna system is demonstrated. A miniaturized stacked dual-band patch antenna for GNSS applications with integrated feed, amplifier, matching, and bias network is considered. Design and manufacturing challenges due to the peculiarities of...conference paper 2024
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Onat, N.B. (author), Yarovoy, Alexander (author), Aslan, Y. (author)The sunflower array topology concept is introduced, for the first time, to the constrained infinitesimal dipole modeling (IDM) technique to increase the computational efficiency and reduce the modeling errors. The concept is applied to embedded element pattern predictions via matrix inversion. A novel study on the impact of the type and...conference paper 2024
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Bosma, S. (author)Millimeter- and submillimeter wave applications, such as point-to-point wireless communications in beyond-5G scenarios, long-range automotive radars and astronomy and astrophysics science cases from space require antennas with high-gain beams that are steerable. At lower (microwave) frequencies, fully sampled phased arrays with thousands of...doctoral thesis 2023
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Patel, Kartik (author), Myers, N.J. (author), Heath, Robert W. (author)Millimeter wave (mmWave) technology can achieve high-speed communication due to the large available spectrum. Furthermore, the use of directional beams in mmWave system provides a natural defense against physical layer security attacks. In practice, however, the beams are imperfect due to mmWave hardware limitations such as the low-resolution...journal article 2023
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Fiorellini Bernardis, A. (author), Sberna, P.M. (author), Bueno Lopez, J. (author), Zhang, H. (author), Llombart, Nuria (author), Neto, A. (author)Drude's description of the response of low-temperature gallium arsenide to optical pulse excitation is used to evaluate the components of a time-domain Norton equivalent circuit of a photoconductive antenna (PCA) source. The saturation of the terahertz (THz) radiated power occurring at large optical excitation levels was previously associated...journal article 2023
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Hehenberger, S.P. (author), Caizzone, Stefano (author), Yarovoy, Alexander (author)The utilization of additive manufacturing (AM) to engineer the permittivity profile of dielectric resonator antennas (DRAs) is considered. For the first time, the capabilities of AM are exploited to create continuously swept permittivity profiles and applied to cylindrical DRAs. The spatial variant lattices (SVL) synthesis algorithm is...journal article 2023
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Çelik, F.T. (author), Joof, Sulayman (author), Karacuha, Kamil (author)The present study proposes a dual-polarized bandwidth-enhanced filtering specialized dipole antenna design for 5G by employing a wide printed dipole, filtering resonators, a reflector surface, and specially designed balun structures. Such a configuration is commonly deployed in conventional base stations. To increase the antenna impedance and...journal article 2023
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Roldan Montero, I. (author), Fioranelli, F. (author), Yarovoy, Alexander (author)A novel framework to enhance the angular resolution of automotive radars is proposed. An approach to enlarge the antenna aperture using artificial neural networks is developed using a self-supervised learning scheme. Data from a high angular resolution radar, i.e., a radar with a large antenna aperture, is used to train a deep neural network...journal article 2023
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Zhang, H. (author), Dabironezare, Shahab Oddin (author), Baselmans, J.J.A. (author), Llombart, Nuria (author)Large format focal plane arrays (FPAs) of dielectric lenses are promising candidates for wide field-of-view submillimeter imagers. In this work, we optimize the scanning gain of such imagers via shaping lens surfaces. We develop an optimization procedure using a field correlation technique between the fields generated by a reflector on the...journal article 2023
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Bueno Lopez, J. (author), Sberna, P.M. (author), Fiorellini Bernardis, A. (author), Zhang, H. (author), Neto, A. (author), Llombart, Nuria (author)State-of-the-art THz pulsed commercial systems operating over large bandwidth suffer from high dispersion or low radiation efficiency due to the poor coupling between the transmitter and receiver photoconductive antennas (PCAs). In this work, we present the fabrication and characterization of a leaky-lens PCA that has the potential to solve...journal article 2023