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Christophe Caloz - One of the best experts on this subject based on the ideXlab platform.

  • general metasurface synthesis based on susceptibility tensors
    IEEE Transactions on Antennas and Propagation, 2015
    Co-Authors: Karim Achouri, Mohamed A Salem, Christophe Caloz
    Abstract:

    A general method, based on susceptibility tensors, is proposed for the synthesis of metasurfaces transforming arbitrary incident Waves into arbitrary reflected and transmitted Waves. The proposed method exhibits two advantages: 1) it is inherently vectorial, and therefore better suited for full vectorial (beyond paraxial) electromagnetic problems; 2) it provides closed-form solutions, and is therefore extremely fast. Incidentally, the method reveals that a metasurface is fundamentally capable to transform up to four independent wave triplets (incident, reflected, and Refracted Waves). In addition, this paper provides the closed-form expressions relating the synthesized susceptibilities and the scattering parameters simulated within periodic boundary conditions, which allows one to design the scattering particles realizing the desired susceptibilities. The versatility of the method is illustrated by examples of metasurfaces achieving the following transformations: generalized refraction, reciprocal and nonreciprocal polarization rotation, Bessel vortex beam generation, and orbital angular momentum multiplexing.

  • General Metasurface Synthesis Based on Susceptibility Tensors
    IEEE Transactions on Antennas and Propagation, 2015
    Co-Authors: Karim Achouri, Mohamed A Salem, Christophe Caloz
    Abstract:

    A general method, based on susceptibility tensors, is proposed for the synthesis of metasurfaces transforming arbitrary incident Waves into arbitrary reflected and transmitted Waves. The proposed method exhibits two advantages: 1)it is inherently vectorial, and therefore better suited for full vectorial (beyond paraxial) electromagnetic problems, 2) it provides closed-form solutions, and is therefore extremely fast. Incidentally, the method reveals that a metasurface is fundamentally capable to transform up to four independent wave triplets (incident, reflected and Refracted Waves). In addition, the paper provides the closed-form expressions relating the synthesized susceptibilities and the scattering parameters simulated within periodic boundary conditions, which allows one to design the scattering particles realizing the desired susceptibilities. The versatility of the method is illustrated by examples of metasurfaces achieving the following transformations: generalized refraction, reciprocal and non-reciprocal polarization rotation, Bessel vortex beam generation, and orbital angular momentum multiplexing.

Karim Achouri - One of the best experts on this subject based on the ideXlab platform.

  • general metasurface synthesis based on susceptibility tensors
    IEEE Transactions on Antennas and Propagation, 2015
    Co-Authors: Karim Achouri, Mohamed A Salem, Christophe Caloz
    Abstract:

    A general method, based on susceptibility tensors, is proposed for the synthesis of metasurfaces transforming arbitrary incident Waves into arbitrary reflected and transmitted Waves. The proposed method exhibits two advantages: 1) it is inherently vectorial, and therefore better suited for full vectorial (beyond paraxial) electromagnetic problems; 2) it provides closed-form solutions, and is therefore extremely fast. Incidentally, the method reveals that a metasurface is fundamentally capable to transform up to four independent wave triplets (incident, reflected, and Refracted Waves). In addition, this paper provides the closed-form expressions relating the synthesized susceptibilities and the scattering parameters simulated within periodic boundary conditions, which allows one to design the scattering particles realizing the desired susceptibilities. The versatility of the method is illustrated by examples of metasurfaces achieving the following transformations: generalized refraction, reciprocal and nonreciprocal polarization rotation, Bessel vortex beam generation, and orbital angular momentum multiplexing.

  • General Metasurface Synthesis Based on Susceptibility Tensors
    IEEE Transactions on Antennas and Propagation, 2015
    Co-Authors: Karim Achouri, Mohamed A Salem, Christophe Caloz
    Abstract:

    A general method, based on susceptibility tensors, is proposed for the synthesis of metasurfaces transforming arbitrary incident Waves into arbitrary reflected and transmitted Waves. The proposed method exhibits two advantages: 1)it is inherently vectorial, and therefore better suited for full vectorial (beyond paraxial) electromagnetic problems, 2) it provides closed-form solutions, and is therefore extremely fast. Incidentally, the method reveals that a metasurface is fundamentally capable to transform up to four independent wave triplets (incident, reflected and Refracted Waves). In addition, the paper provides the closed-form expressions relating the synthesized susceptibilities and the scattering parameters simulated within periodic boundary conditions, which allows one to design the scattering particles realizing the desired susceptibilities. The versatility of the method is illustrated by examples of metasurfaces achieving the following transformations: generalized refraction, reciprocal and non-reciprocal polarization rotation, Bessel vortex beam generation, and orbital angular momentum multiplexing.

S. K. Tomar - One of the best experts on this subject based on the ideXlab platform.

  • reflection refraction of a dilatational wave at a plane interface between uniform elastic and swelling porous half spaces
    Transport in Porous Media, 2015
    Co-Authors: Suraj Goyal, S. K. Tomar
    Abstract:

    The present work deals with the reflection and refraction phenomena of a plane dilatational wave striking obliquely at a plane interface between a uniform elastic half-space and a swelling porous elastic half-space. The swelling porous half-space consists of solid, liquid (viscous) and gas (inviscid) constituents. Two problems have been considered: (1) when the inhomogeneous dilatational wave is made incident at the interface after propagating through the porous half-space (2) when the homogeneous dilatational wave is made incident at the interface after propagating through the uniform elastic solid half-space. The equations giving the amplitude ratios and the expressions for the partition of incident energy among various reflected/Refracted Waves have been presented. Numerical computations have been performed for a specific model consisting of sandstone, water (viscous) and carbon dioxide as solid, liquid and gas phases, respectively, of the porous medium and granite stone as a uniform elastic medium. The variations of amplitude ratios and corresponding energy ratios against the angle of incidence and frequency have been illustrated graphically. It has been verified that during reflection/refraction phenomena, the sum of energy ratios is equal to unity at each angle of incidence.

  • longitudinal wave response of a chiral slab interposed between micropolar solid half spaces
    International Journal of Solids and Structures, 2009
    Co-Authors: Aarti Khurana, S. K. Tomar
    Abstract:

    A plane longitudinal displacement wave is made incident upon a chiral slab of uniform thickness, interposed between two different semi-infinite micropolar elastic solids. The amplitude ratios of various reflected and Refracted Waves are obtained using the two possible sets of boundary conditions. The variations of various amplitude ratios with the angle of incidence as well as with the frequency are depicted graphically, for a specific problem. The effect of chirality parameter and the thickness of the chiral slab on these amplitude ratios have been noticed. Results of some earlier researchers have also been reduced as special cases of present formulation.

  • reflection and transmission of elastic Waves at an elastic porous solid saturated by two immiscible fluids
    International Journal of Solids and Structures, 2006
    Co-Authors: S. K. Tomar, Ashish Arora
    Abstract:

    Wave propagation in a porous elastic medium saturated by two immiscible fluids is investigated. It is shown that there exist three dilatational Waves and one transverse wave propagating with different velocities. It is found that the velocities of all the three longitudinal Waves are influenced by the capillary pressure, while the velocity of transverse wave does not at all. The problem of reflection and refraction phenomena due to longitudinal and transverse wave incident obliquely at a plane interface between uniform elastic solid half-space and porous elastic half-space saturated by two immiscible fluids has been analyzed. The amplitude ratios of various reflected and Refracted Waves are found to be continuous functions of the angle of incidence. Expression of energy ratios of various reflected and Refracted Waves are derived in closed form. The amplitude ratios and energy ratios have been computed numerically for a particular model and the results obtained are depicted graphically. It is verified that during transmission there is no dissipation of energy at the interface. Some particular cases have also been reduced from the present formulation.

Mohamed A Salem - One of the best experts on this subject based on the ideXlab platform.

  • general metasurface synthesis based on susceptibility tensors
    IEEE Transactions on Antennas and Propagation, 2015
    Co-Authors: Karim Achouri, Mohamed A Salem, Christophe Caloz
    Abstract:

    A general method, based on susceptibility tensors, is proposed for the synthesis of metasurfaces transforming arbitrary incident Waves into arbitrary reflected and transmitted Waves. The proposed method exhibits two advantages: 1) it is inherently vectorial, and therefore better suited for full vectorial (beyond paraxial) electromagnetic problems; 2) it provides closed-form solutions, and is therefore extremely fast. Incidentally, the method reveals that a metasurface is fundamentally capable to transform up to four independent wave triplets (incident, reflected, and Refracted Waves). In addition, this paper provides the closed-form expressions relating the synthesized susceptibilities and the scattering parameters simulated within periodic boundary conditions, which allows one to design the scattering particles realizing the desired susceptibilities. The versatility of the method is illustrated by examples of metasurfaces achieving the following transformations: generalized refraction, reciprocal and nonreciprocal polarization rotation, Bessel vortex beam generation, and orbital angular momentum multiplexing.

  • General Metasurface Synthesis Based on Susceptibility Tensors
    IEEE Transactions on Antennas and Propagation, 2015
    Co-Authors: Karim Achouri, Mohamed A Salem, Christophe Caloz
    Abstract:

    A general method, based on susceptibility tensors, is proposed for the synthesis of metasurfaces transforming arbitrary incident Waves into arbitrary reflected and transmitted Waves. The proposed method exhibits two advantages: 1)it is inherently vectorial, and therefore better suited for full vectorial (beyond paraxial) electromagnetic problems, 2) it provides closed-form solutions, and is therefore extremely fast. Incidentally, the method reveals that a metasurface is fundamentally capable to transform up to four independent wave triplets (incident, reflected and Refracted Waves). In addition, the paper provides the closed-form expressions relating the synthesized susceptibilities and the scattering parameters simulated within periodic boundary conditions, which allows one to design the scattering particles realizing the desired susceptibilities. The versatility of the method is illustrated by examples of metasurfaces achieving the following transformations: generalized refraction, reciprocal and non-reciprocal polarization rotation, Bessel vortex beam generation, and orbital angular momentum multiplexing.

J C Gehrels - One of the best experts on this subject based on the ideXlab platform.

  • ground penetrating radar for determining volumetric soil water content results of comparative measurements at two test sites
    Journal of Hydrology, 1997
    Co-Authors: R A Van Overmeeren, S V Sariowan, J C Gehrels
    Abstract:

    Ground penetrating radar (GPR) can provide information on the soil water content of the unsaturated zone in sandy deposits via measurements from the surface, and so avoids drilling. Proof of this was found from measurements of radar wave velocities carried out ten times over 13 months at two test sites in the Netherlands. At these same locations and on the same dates, soil water content was measured in access robes using a capacitance probe. Comparison of GPR and capacitance probe observations revealed that: 1. The inferred absolute values of soil water content agree well. This is remarkable because the soil water content is deduced entirely differently for the two methods. 2. Seasonal fluctuations in soil water content established for different (general) depth zones of radar Waves correlate well with the fluctuations observed in the access tubes. 3. The various methods to determine the propagation velocities of radar Waves are complementary; together they produce a realistic and reasonably complete image of the vertical distribution of the soil water content of the entire unsaturated zone. High-frequency (200 MHz) direct groundWaves and Refracted Waves constitute a particularly attractive complementary combination, which provides information on consecutive shallow zones in the underground, i.e. the zones of major soil water content fluctuations. 4. Lateral variations established at one of the test sites where several access tubes have been placed in a transect also follow from the GPR measurements along that profile; this non-destructive determination of soil water content in practically continuous and detailed sections is one of the great assets of GPR, opening the way to mapping preferential soil water flow paths.