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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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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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van Schelven, R.M. (author), Syed, Waqas (author), Carluccio, G. (author), Doris, Kostas (author), de Graauw, Anton (author), Neto, A. (author), Cavallo, D. (author)In this work, we investigate antenna architectures to implement dual-mode operation in phased array designs. Planar slot antenna elements are used in array configuration, in combination with artificial dielectrics layers (ADLs) located in the close proximity of the array, to achieve pattern shaping. The artificial dielectric superstrate...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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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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Gu, Junhong (author), Neto, A. (author), Lager, I.E. (author), Stumpf, Martin (author)The pulsed electromagnetic (EM) field radiated by a gap-fed, long slot in a perfectly conducting thin sheet located in between dielectric and free-space subdomains is examined. A phenomenological interpretation of the so-called head wave (HW) constituent is proposed, this fostering the understanding of the complex EM behaviour at, and...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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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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Ozzola, R. (author), Cavallo, D. (author), Neto, A. (author)We present a study on beam coupling in radiating structures that support multiple simultaneous beams. The formation of multiple beams is relevant in modern wireless communication applications when diverse data streams can be sent from a single transmitter to users located in different directions. General expressions are provided that relate...journal article 2022
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Van Katwijk, Alexander J. (author), Neto, A. (author), Toso, Giovanni (author), Cavallo, D. (author)We present an efficient method for the analysis of finite connected slot arrays in the presence of stratified media. The formulation is based on a spectral method of moments, where only one basis function is considered for each array element and one for each slot edge. An expression for the mutual impedance is derived in terms of a double...journal article 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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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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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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Ozzola, R. (author), Geng, J. (author), Neto, A. (author), Freni, A. (author)The thermal emission from finite-size bodies is directly investigated without resorting to reciprocity. Specifically, an integral equation representing the electromagnetic field distribution on a conductive body under investigation is proposed. The source of the electromagnetic field is classic as it is an extension of Johnson noise sources to...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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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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van Schelven, R.M. (author), Fiorellini Bernardis, A. (author), Sberna, P.M. (author), Neto, A. (author)Semiconductor (SC)-based bulk absorbers operating in the (sub-) THz range are discussed. The conductivities of the bulk media are described by the Drude model for electron gas where the electron density is controlled. The Drude model predicts the existence of two frequencies of interest: one associated with the scattering time of the electrons...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