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Garufo, A. (author), Carluccio, G. (author)Analytical formulations of the active admittance and impedance of connected arrays based on dipole and slot antennas, respectively, when elements are arranged in a hexagonal lattice, are presented. Different canonical dielectric layers stratifications are considered. The formulations is based on multi-layer Green’s function spectral...conference paper 2022
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Martins, J.E. (author), Weemstra, C. (author), Ruigrok, E. (author), Verdel, A. (author), Jousset, P. (author), Hersir, G.P. (author)Tomographic imaging based on ambient seismic noise measurements has shown to be a powerful tool, especially in areas like Iceland, where the microseism illumination is excellent. In this paper, we produce a 3D S-wave tomographic image over the western Reykjanes Peninsula high-enthalpy geothermal fields and evaluate the reliability of the...article 2019
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Boullenger, B. (author), Verdel, A. (author), Thorbecke, J. (author), Draganov, D. (author)Since 2008, CO2 has been injected at the demonstration site for CO2 sequestration in Ketzin, Germany. Since 2009, a permanent array of seismic receivers installed by TNO at the injection site has recorded passive data continuously. It is the intention of TNO to use seismic interferometry (SI) by cross-correlation applied to the recorded ambient...conference paper 2013
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Cavallo, D. (author), Neto, A. (author), Gerini, G. (author)Wideband arrays of printed dipoles with inter-element loads are investigated. A closed-form expression for the active input impedance of the array element is derived with a spectral domain approach. The procedure is based on an extension of the Green's function formulation for arrays of connected dipoles to the case of dipoles coupled via loads....article 2012
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Neto, A. (author), Cavallo, D. (author), Gerini, G. (author)This paper presents a Green's function based procedure to assess edge effects in finite wideband connected arrays. Truncation effects are more severe in broadband arrays, since the inter-element mutual coupling facilitates the propagation of edge-born waves that can become dominant over large portions of the arrays. As a consequence, the overall...conference paper 2011
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Cavallo, D. (author), Neto, A. (author), Gerini, G. (author)Connected arrays constitute the only family of antenna arrays for which the spectral Green's Functions have been derived analytically. This formalism is extended here to the receiving case. When the arrays are assumed to be infinitely extended and periodically excited, rigorous equivalent networks can be derived to represent the electromagnetic...article 2011
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Neto, A. (author), Llombart, N. (author), Gerini, G. (author), Bonnedal, M. (author), de Maagt, P. (author), TNO Defensie en Veiligheid (author)The design strategy that uses dielectric super-layers with neighboring wave-guides closed in matched loads constitutes a worst case scenario as far as the performance enhancement is concerned and finds applicability in radiometric imaging arrays. On the other side the design strategy that uses dielectric super-layers with neighboring wave-guides...conference paper 2007
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Neto, A. (author), Gerini, G. (author), Bruni, S. (author), Maci, S. (author), TNO Defensie en Veiligheid (author)An array of long slots, oriented along x, etched on a ground plane that separates two infinite dielectric materials constitutes the basic canonical problem investigated in this article. In a single slot structure, the direction of radiation and the attenuation constant could be directly linked to the dominant leaky wave pole (kxlw) that...conference paper 2007
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Neto, A. (author), Llombart, N. (author), Gerini, G. (author), Bonnedal, M.D. (author), de Maagt, P. (author), TNO Defensie en Veiligheid (author)We describe the use of electromagnetic bandgap (EBG) super-layers to improve the shape of reflectors illumination function. Following an investigation of the leaky wave pole singularities of the EBG Green's function, the shape of the radiation patterns of small apertures in ground planes are optimized. The maximization of the reflector aperture...article 2007
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Neto, A. (author), Llombart, N. (author), TNO Defensie en Veiligheid (author)This letter discusses the properties of printed antennas whose radiation patterns (their directivity or their shape) are enhanced by means of dielectric superlayers which support leaky waves. In particular the characterizing complex leaky wave poles of the spectral Green Function are approximated analytically, for the first time over large...article 2006
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Monni, S. (author), Neto, A. (author), Tijhuis, A.G. (author), TNO Defensie en Veiligheid (author)Despite the fact that the general behavior of periodic structures has been investigated for many decades, the analysis and design of multilayered FSS's is still a very actual and complicated problem. This is especially true for stringent requirements, which rise for example when the FSS has to be integrated with a planar phased array. A MEN...conference paper 2006
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Neto, A. (author), Lee, J.J. (author), TNO Defensie en Veiligheid (author)In this paper the ultrawide-band properties of a long slot array are described. The study provides the rigorously derived Green’s function (GF) for an infinite long slot array. FromtheseGF active impedances and radiation patterns for various cases were obtained. The ultrawide bandwidths and the array performances of such apertures are...article 2006
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Gerini, G. (author), Maci, S. (author), Bruni, S. (author), Llombart, N. (author), Neto, A. (author), TNO Defensie en Veiligheid (author)Problem matched basis functions are proposed for the method of moments analysis of printed slot coupled microstrips. The appropriate equivalent currents of the integral equation kernel are represented in terms of two sets of entire domain basis functions. These functions synthesize on one hand the resonant behavior of slots, microstrips or...article 2005
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Bruni, S. (author), Llombart Juan, N. (author), Neto, A. (author), Gerini, G. (author), Maci, S. (author), TNO Fysisch en Elektronisch Laboratorium (author)A general algorithm for the analysis of microstrip coupled leaky wave slot antennas was discussed. The method was based on the construction of physically appealing entire domain Methods of Moments (MoM) basis function that allowed a consistent reduction of the number of unknowns and of total computation time. The basis function obtained were...conference paper 2004
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Maci, S. (author), Neto, A. (author)This second part of a two-paper sequence deals with the uniform asymptotic description of the Green's function of an infinite slot printed between two different homogeneous dielectric media. Starting from the magnetic current derived in Part I, the dyadic green's function is first formulated in integral form in both spectral and spatial domains;...article 2004
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TNO Defensie en Veiligheid (author), Bruni, S. (author), Llombart, N. (author), Neto, A. (author), Gerini, G. (author), Maci, S. (author)A method is proposed for the analysis of arrays of linear printed antennas. After the formulation of pertinent set of integral equations, the appropriate equivalent currents of the Method of Moments are represented in terms of two sets of entire domain basis functions. These functions synthesize on one side the resonant behavior of the slot,...conference paper 2004
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Neto, A. (author), de Maagt, P. (author), Maci, S. (author)A method is proposed for the analysis of slot antennas excited by coplanar waveguides. First, a standard integral equation for the continuity of the magnetic field is formulated. Then the appropriate equivalent magnetic currents of the method of moments are represented in terms of entire-domain basis functions which synthesize the resonant...article 2003
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Neto, A. (author), Maci, S. (author), TNO Fysisch en Elektronisch Laboratorium (author)This sequence of papers presents an analytical closed form for the Green's function of an infinite slot printed between two different homogeneous dielectrics. This first part is devoted to the derivation of the slot magnetic current and to the discussion of the relevant physical implications. The Fourier spectrum of the magnetic current is...article 2003
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Neto, A. (author)With the introduction of the "True" Physical Optics, the source in the far field of the canonical structure was not assumed but instead to use the exact dielectric slab's GF's in orde to obtain a more accurate approximation of the PO currents in both the external and the internal sides of the radome. Indeed the PO approximation, consists only in...conference paper 2003
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Vossen, S.H.J.A. (author), Tijhuis, A.G. (author), Lepelaars, E.S.A.M. (author), Zwamborn, A.P.M. (author), TNO Fysisch en Elektronisch Laboratorium (author)The use of two identical straight thin-wire antennas for the detection of a buried wire is analyzed with the aid of numerical calculations. The buried wire is located below an interface between two homogeneous half-spaces. The detection setup, which is formed by a transmitting and a receiving wire, is located above the interface. The transmitter...article 2002
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