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Dabironezare, Shahab Oddin (author), Nair, A. (author), Neto, A. (author), Llombart, Nuria (author)The use of lens arrays in (sub)-millimeter sensing and communication applications will enable the development of integrated antenna front-ends with multiple independent beams as well as dynamic scanning capabilities. In applications such as MIMO communications, interferometric arrays, and Tx/Rx duplexing capabilities, a key parameter is the...journal article 2024
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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
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Neto, A. (author), Llombart, Nuria (author), Freni, Angelo (author)In the circuit theory, the Norton and Thevenin equivalent generators are tools that simplify the solutions of networks involving passive or active components. They have been extensively used in the frequency domain to describe time-harmonic sources. A time-stepped evolution is instead typically used to include transient sources. As a...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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Huiskes, M.D. (author), Bueno Lopez, J. (author), Llombart, Nuria (author), Neto, A. (author)Photoconductive antennas (PCAs) are used for imaging and sensing applications because of their ability to radiate short pulses with large bandwidths in the THz regime. The characterization of PCAs has previously been done using a time-domain Norton equivalent circuit. Thanks to a recent contribution, the size of the excited photoconductive area...conference paper 2023
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Zhang, H. (author), Bueno Lopez, J. (author), Sberna, P.M. (author), Llombart, Nuria (author), Neto, A. (author)Photoconductive antennas (PCAs) are promising candidates for sensing and imaging systems. We have investigated their properties under pulsed laser illumination both in transmission and reception. First, a transmitting PCA has been characterized including a power measurement. Then, a Quasi-Optical (QO) link between a transmitter and a receiver...conference paper 2023
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Hoogelander, M. (author), van Berkel, S.L. (author), Malotaux, E.S. (author), Alonso Del Pino, M. (author), Spirito, M. (author), Neto, A. (author), Cavallo, D. (author), Llombart, Nuria (author)In this contribution we will present the diffraction-limited imaging capabilities of a focal plane array (FPA) of antenna-coupled direct-detectors at submillimeter wavelengths. The FPA prototype is a tightly sampled, 12-pixel array that was developed in a 22 nm CMOS technology and it covers a band from 200 GHz to 600 GHz. A quasi-optical (QO)...conference paper 2022
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Bueno Lopez, J. (author), Huiskes, M. (author), Zhang, H. (author), Sberna, P.M. (author), Llombart, Nuria (author), Neto, A. (author)Photoconductive antennas are devices that provide power up to THz frequencies at a relatively low cost. However, the power radiated by each antenna is typically quite low and arrays have been proposed to increase it. In this paper we present the design of a leaky enhanced array architecture that surpasses the state of the art as it operates...conference paper 2022
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Ozzola, R. (author), Geng, J. (author), Llombart, Nuria (author), Freni, A. (author), Cavallo, D. (author), Neto, A. (author)A Volumetric Method of Moments accelerated by means of iterative solvers combined with FFT matrix-vector products has been presented. The method allows analyzing small lens antennas with their integrated feeds efficiently since different structures and geometries can be studied with the same discretization, just by adding the material...conference paper 2022
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Nair, A. (author), Dabironezare, Shahab Oddin (author), Neto, A. (author), Llombart, Nuria (author)Future applications in sensing and communications at (sub)-millimetre wavelengths will benefit from having large integrated coherent arrays. The use of lens arrays will enable the fabrication of integrated antenna front-ends with many potential independent beams as well as dynamic scanning capabilities. For applications such as MIMO...conference paper 2022
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Bosma, S. (author), Neto, A. (author), Llombart, Nuria (author)In this work, we show that the near field of leaky-wave resonant antennas (LWAs) radiating into a dense medium can be locally represented as a spherical wave in a certain solid angle around broadside using an accurate definition of the phase center. The near field in this solid angle can be efficiently evaluated through the integration of the...journal article 2022
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Ozzola, R. (author), Cavallo, D. (author), Freni, Angelo (author), Llombart, Nuria (author), Neto, A. (author)The number of independent links that can be hosted by an antenna platform for Line-of-Sight (LoS) communications is limited by its physical size and the interference between the beams associated with different users. For large-size platforms, the interference can be reduced by compromising the aperture efficiency, and this trade-off is the...journal article 2022
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Zhang, H. (author), Dabironezare, Shahab Oddin (author), Carluccio, G. (author), Neto, A. (author), Llombart, Nuria (author)We present a freely accessible graphical user interface (GUI) for analyzing antenna-fed quasi-optical (QO) systems in reception (Rx). This analysis is presented here for four widely used canonical QO components: parabolic reflectors and elliptical, extended hemispherical, and hyperbolic lenses. The employed methods are geometrical optics (GO)...journal article 2021
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Fiorellini Bernardis, A. (author), Zhang, H. (author), Sberna, P.M. (author), Bueno Lopez, J. (author), Neto, A. (author), Llombart, Nuria (author)The time evolution of voltages and currents in a pulsed photo conductive antenna (PCA) source is evaluated resorting to a rigorous procedure that stems from semiconductor physics first, to define the phenomena involved in the generation of the photocurrent, and then relies on an equivalent circuit in time domain, providing a direct estimation...abstract 2021
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Zhang, H. (author), Bosma, S. (author), Neto, A. (author), Llombart, Nuria (author)A dual-polarized 4 x 4 scanning phased array antenna with leaky-wave enhanced lenses operating at 28 GHz is presented. Such an antenna can be used for point-to-point fifth-generation (5G) communications that require high gain, wide bandwidth (BW), and limited steering ranges. The proposed array has a periodicity of two wavelengths, and the...journal article 2021
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van Berkel, S.L. (author), Malotaux, E.S. (author), De Martino, C. (author), Spirito, M. (author), Cavallo, D. (author), Neto, A. (author), Llombart, Nuria (author)A complete system modeling and characterization of a wideband differential terahertz (THz) direct detector, integrated in a commercial CMOS technology, is presented. The detector consists of a recently developed double leaky-slot lens antenna that operates from 200 to 600 GHz in combination with a differential Schottky barrier diode (SBD) direct...journal article 2021
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Neto, A. (author), Fiorellini Bernardis, A. (author), Emer, Diego (author), Freni, Angelo (author), Llombart, Nuria (author)The observable field is defined as the portion of the incident field that can contribute to the power received by an antenna. Recently, the observable field was estimated for a plane wave incidence. Here, the procedure is extended to a general incident field expressed as a superposition of homogeneous plane waves. The observable field concept...journal article 2020
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Arias Campo, M. (author), Blanco, Darwin (author), Neto, A. (author), Llombart, Nuria (author), Bruni, Simona (author)In order to fulfill the exponential increase in the demand of high-speed wireless links, future XG wireless networks will be developed at higher carrier signal frequencies, reaching the hundreds of gigahertz. In this contribution, a leaky-wave-fed HDPE lens antenna working at ${G}$ -band which can be useful for future XG communications is...journal article 2020
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Hähnle, S.A. (author), Yurduseven, Ozan (author), van Berkel, S.L. (author), Llombart, Nuria (author), Bueno, Juan (author), Yates, Stephen J.C. (author), Murugesan, Vignesh (author), Thoen, David (author), Neto, A. (author), Baselmans, J.J.A. (author)We present the design, fabrication, and characterization of a broadband leaky lens antenna for broadband, spectroscopic imaging applications. The antenna is designed for operation in the 300-900 GHz band. We integrate the antenna directly into an Al-NbTiN hybrid microwave kinetic inductance detector (MKID) to measure the beam pattern and...journal article 2020
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Dabironezare, Shahab Oddin (author), Carluccio, G. (author), Freni, Angelo (author), Neto, A. (author), Llombart, Nuria (author)Future sub millimeter imagers are being developed with large focal plane arrays (FPAs) of lenses to increase the field of view (FoV) and the imaging speed. A full-wave electromagnetic analysis of such arrays is numerically cumbersome and time-consuming. This article presents a spectral technique based on Fourier optics combined with...journal article 2020