The Experts below are selected from a list of 5673 Experts worldwide ranked by ideXlab platform
Olav Breinbjerg - One of the best experts on this subject based on the ideXlab platform.
-
a review of the scattering parameter extraction method with clarification of ambiguity issues in relation to metamaterial homogenization
IEEE Antennas and Propagation Magazine, 2013Co-Authors: Samel Arslanagic, T. V. Hansen, A. H. Gregersen, Niels Asger Mortensen, Richard W. Ziolkowski, Ole Sigmund, Olav BreinbjergAbstract:The scattering-parameter extraction method of metamaterial homogenization is reviewed to show that the only ambiguity is that related to the choice of the branch of the complex logarithmic function (or the complex inverse cosine function). It is shown that the method has no ambiguity for the sign of the wavenumber and Intrinsic Impedance. While the method indeed yields two signs for the Intrinsic Impedance and thus the wavenumber, the signs are dependent. Moreover, both sign combinations lead to the same permittivity and permeability, and are thus permissible. This observation is in distinct contrast to a number of statements in the literature where the correct sign of the Intrinsic Impedance and wavenumber resulting from the scattering-parameter method is chosen by imposing additional physical requirements, such as passivity. The scattering-parameter method is reviewed through an investigation of a uniform plane wave normally incident on a planar slab in free space. The severity of the branch ambiguity is illustrated through simulations of a known metamaterial realization. Several approaches for proper branch selection are reviewed, and the suitability to metamaterial samples is discussed.
-
A review of the scattering-parameter extraction method with clarification of ambiguity issues in relation to metamaterial homogenization
IEEE Antennas and Propagation Magazine, 2013Co-Authors: S. Arslanagić, T. V. Hansen, A. H. Gregersen, Niels Asger Mortensen, Richard W. Ziolkowski, Ole Sigmund, Olav BreinbjergAbstract:The scattering parameter extraction method of metamaterial homogenization is reviewed to show that the only ambiguity is the one related to the choice of the branch of the complex logarithmic function (or the complex inverse cosine function), whereas it has no ambiguity for the sign of the wave number and Intrinsic Impedance. While the method indeed yields two signs of the Intrinsic Impedance, and thus the wave number, the signs are dependent, and moreover, both sign combinations lead to the same permittivity and permeability, and are thus permissible. This observation is in distinct contrast to a number of statements in the literature where the correct sign of the Intrinsic Impedance and wave number, resulting from the scattering parameter method, is chosen by imposing additional physical requirements such as passivity. The scattering parameter method is reviewed through an investigation of a uniform plane wave normally incident on a planar slab in free-space, and the severity of the branch ambiguity is illustrated through simulations of a known metamaterial realization. Several approaches for proper branch selection are reviewed and their suitability to metamaterial samples is discussed.
Charles A E Little - One of the best experts on this subject based on the ideXlab platform.
-
modeling electrical double layer effects for microfluidic Impedance spectroscopy from 100 khz to 110 ghz
Lab on a Chip, 2017Co-Authors: Charles A E Little, Nathan D Orloff, Isaac E Hanemann, Christian J Long, Victor M Bright, James C BoothAbstract:Broadband microfluidic-based Impedance spectroscopy can be used to characterize complex fluids, with applications in medical diagnostics and in chemical and pharmacological manufacturing. Many relevant fluids are ionic; during Impedance measurements ions migrate to the electrodes, forming an electrical double-layer. Effects from the electrical double-layer dominate over, and reduce sensitivity to, the Intrinsic Impedance of the fluid below a characteristic frequency. Here we use calibrated measurements of saline solution in microfluidic coplanar waveguide devices at frequencies between 100 kHz and 110 GHz to directly measure the double-layer admittance for solutions of varying ionic conductivity. We successfully model the double-layer admittance using a combination of a Cole–Cole response with a constant phase element contribution. Our analysis yields a double-layer relaxation time that decreases linearly with solution conductivity, and allows for double-layer effects to be separated from the Intrinsic fluid response and quantified for a wide range of conducting fluids.
James C Booth - One of the best experts on this subject based on the ideXlab platform.
-
modeling electrical double layer effects for microfluidic Impedance spectroscopy from 100 khz to 110 ghz
Lab on a Chip, 2017Co-Authors: Charles A E Little, Nathan D Orloff, Isaac E Hanemann, Christian J Long, Victor M Bright, James C BoothAbstract:Broadband microfluidic-based Impedance spectroscopy can be used to characterize complex fluids, with applications in medical diagnostics and in chemical and pharmacological manufacturing. Many relevant fluids are ionic; during Impedance measurements ions migrate to the electrodes, forming an electrical double-layer. Effects from the electrical double-layer dominate over, and reduce sensitivity to, the Intrinsic Impedance of the fluid below a characteristic frequency. Here we use calibrated measurements of saline solution in microfluidic coplanar waveguide devices at frequencies between 100 kHz and 110 GHz to directly measure the double-layer admittance for solutions of varying ionic conductivity. We successfully model the double-layer admittance using a combination of a Cole–Cole response with a constant phase element contribution. Our analysis yields a double-layer relaxation time that decreases linearly with solution conductivity, and allows for double-layer effects to be separated from the Intrinsic fluid response and quantified for a wide range of conducting fluids.
Ole Sigmund - One of the best experts on this subject based on the ideXlab platform.
-
a review of the scattering parameter extraction method with clarification of ambiguity issues in relation to metamaterial homogenization
IEEE Antennas and Propagation Magazine, 2013Co-Authors: Samel Arslanagic, T. V. Hansen, A. H. Gregersen, Niels Asger Mortensen, Richard W. Ziolkowski, Ole Sigmund, Olav BreinbjergAbstract:The scattering-parameter extraction method of metamaterial homogenization is reviewed to show that the only ambiguity is that related to the choice of the branch of the complex logarithmic function (or the complex inverse cosine function). It is shown that the method has no ambiguity for the sign of the wavenumber and Intrinsic Impedance. While the method indeed yields two signs for the Intrinsic Impedance and thus the wavenumber, the signs are dependent. Moreover, both sign combinations lead to the same permittivity and permeability, and are thus permissible. This observation is in distinct contrast to a number of statements in the literature where the correct sign of the Intrinsic Impedance and wavenumber resulting from the scattering-parameter method is chosen by imposing additional physical requirements, such as passivity. The scattering-parameter method is reviewed through an investigation of a uniform plane wave normally incident on a planar slab in free space. The severity of the branch ambiguity is illustrated through simulations of a known metamaterial realization. Several approaches for proper branch selection are reviewed, and the suitability to metamaterial samples is discussed.
-
A review of the scattering-parameter extraction method with clarification of ambiguity issues in relation to metamaterial homogenization
IEEE Antennas and Propagation Magazine, 2013Co-Authors: S. Arslanagić, T. V. Hansen, A. H. Gregersen, Niels Asger Mortensen, Richard W. Ziolkowski, Ole Sigmund, Olav BreinbjergAbstract:The scattering parameter extraction method of metamaterial homogenization is reviewed to show that the only ambiguity is the one related to the choice of the branch of the complex logarithmic function (or the complex inverse cosine function), whereas it has no ambiguity for the sign of the wave number and Intrinsic Impedance. While the method indeed yields two signs of the Intrinsic Impedance, and thus the wave number, the signs are dependent, and moreover, both sign combinations lead to the same permittivity and permeability, and are thus permissible. This observation is in distinct contrast to a number of statements in the literature where the correct sign of the Intrinsic Impedance and wave number, resulting from the scattering parameter method, is chosen by imposing additional physical requirements such as passivity. The scattering parameter method is reviewed through an investigation of a uniform plane wave normally incident on a planar slab in free-space, and the severity of the branch ambiguity is illustrated through simulations of a known metamaterial realization. Several approaches for proper branch selection are reviewed and their suitability to metamaterial samples is discussed.
A. H. Gregersen - One of the best experts on this subject based on the ideXlab platform.
-
a review of the scattering parameter extraction method with clarification of ambiguity issues in relation to metamaterial homogenization
IEEE Antennas and Propagation Magazine, 2013Co-Authors: Samel Arslanagic, T. V. Hansen, A. H. Gregersen, Niels Asger Mortensen, Richard W. Ziolkowski, Ole Sigmund, Olav BreinbjergAbstract:The scattering-parameter extraction method of metamaterial homogenization is reviewed to show that the only ambiguity is that related to the choice of the branch of the complex logarithmic function (or the complex inverse cosine function). It is shown that the method has no ambiguity for the sign of the wavenumber and Intrinsic Impedance. While the method indeed yields two signs for the Intrinsic Impedance and thus the wavenumber, the signs are dependent. Moreover, both sign combinations lead to the same permittivity and permeability, and are thus permissible. This observation is in distinct contrast to a number of statements in the literature where the correct sign of the Intrinsic Impedance and wavenumber resulting from the scattering-parameter method is chosen by imposing additional physical requirements, such as passivity. The scattering-parameter method is reviewed through an investigation of a uniform plane wave normally incident on a planar slab in free space. The severity of the branch ambiguity is illustrated through simulations of a known metamaterial realization. Several approaches for proper branch selection are reviewed, and the suitability to metamaterial samples is discussed.
-
A review of the scattering-parameter extraction method with clarification of ambiguity issues in relation to metamaterial homogenization
IEEE Antennas and Propagation Magazine, 2013Co-Authors: S. Arslanagić, T. V. Hansen, A. H. Gregersen, Niels Asger Mortensen, Richard W. Ziolkowski, Ole Sigmund, Olav BreinbjergAbstract:The scattering parameter extraction method of metamaterial homogenization is reviewed to show that the only ambiguity is the one related to the choice of the branch of the complex logarithmic function (or the complex inverse cosine function), whereas it has no ambiguity for the sign of the wave number and Intrinsic Impedance. While the method indeed yields two signs of the Intrinsic Impedance, and thus the wave number, the signs are dependent, and moreover, both sign combinations lead to the same permittivity and permeability, and are thus permissible. This observation is in distinct contrast to a number of statements in the literature where the correct sign of the Intrinsic Impedance and wave number, resulting from the scattering parameter method, is chosen by imposing additional physical requirements such as passivity. The scattering parameter method is reviewed through an investigation of a uniform plane wave normally incident on a planar slab in free-space, and the severity of the branch ambiguity is illustrated through simulations of a known metamaterial realization. Several approaches for proper branch selection are reviewed and their suitability to metamaterial samples is discussed.
