The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
K Sarabandi - One of the best experts on this subject based on the ideXlab platform.
-
experimental characterization of the effective Propagation Constant of dense random media
IEEE Transactions on Antennas and Propagation, 1999Co-Authors: A Nashashibi, K SarabandiAbstract:A new technique for measuring the effective Propagation Constant of dense random media is presented. This technique involves two major steps: (1) measurement of the mean bistatic scattered field of a cluster of the random medium confined in a spherical boundary and (2) characterization of the complex permittivity for a homogeneous dielectric sphere having identical radius and bistatic scattered field as those of the spherical cluster of the random medium. Using this measurement technique, not only the effective Propagation Constant of complex dense random media for which an analytical solution does not exist can be characterized, but it can also be used to establish the validity region of the existing models. The sensitivity analyses of the proposed algorithm show that the imaginary part of the effective Propagation Constant can be measured very accurately. It is also shown that the effective complex permittivity of media with very low dielectric contrast or volume fractions can be characterized accurately. Measurements of the effective Propagation Constant of different dense random media comprised of homogeneous spherical particles of different packing densities are reported and compared with the existing analytical models.
-
A technique for measuring the effective Propagation Constant of dense random media
IEEE Antennas and Propagation Society International Symposium. 1995 Digest, 1995Co-Authors: A Nashashibi, K SarabandiAbstract:The measurement technique considered in this paper has a significant impact on the modelling of electromagnetic scattering from dense random media. A method for measuring the effective Propagation Constant, K, directly is presented which is not restricted by the particle size, shape and density. The effective dielectric Constant of the medium is evaluated from the mean bistatic scattered fields of a cluster of the random medium confined in a geometrical boundary. In this approach, the mean scattered fields are fitted to the bistatic scattered fields of a homogeneous lossy material having the same geometrical boundary. The bistatic measurement technique is based on a novel technique where only a monostatic radar and a rotatable ground plane are needed.
A Nashashibi - One of the best experts on this subject based on the ideXlab platform.
-
experimental characterization of the effective Propagation Constant of dense random media
IEEE Transactions on Antennas and Propagation, 1999Co-Authors: A Nashashibi, K SarabandiAbstract:A new technique for measuring the effective Propagation Constant of dense random media is presented. This technique involves two major steps: (1) measurement of the mean bistatic scattered field of a cluster of the random medium confined in a spherical boundary and (2) characterization of the complex permittivity for a homogeneous dielectric sphere having identical radius and bistatic scattered field as those of the spherical cluster of the random medium. Using this measurement technique, not only the effective Propagation Constant of complex dense random media for which an analytical solution does not exist can be characterized, but it can also be used to establish the validity region of the existing models. The sensitivity analyses of the proposed algorithm show that the imaginary part of the effective Propagation Constant can be measured very accurately. It is also shown that the effective complex permittivity of media with very low dielectric contrast or volume fractions can be characterized accurately. Measurements of the effective Propagation Constant of different dense random media comprised of homogeneous spherical particles of different packing densities are reported and compared with the existing analytical models.
-
A technique for measuring the effective Propagation Constant of dense random media
IEEE Antennas and Propagation Society International Symposium. 1995 Digest, 1995Co-Authors: A Nashashibi, K SarabandiAbstract:The measurement technique considered in this paper has a significant impact on the modelling of electromagnetic scattering from dense random media. A method for measuring the effective Propagation Constant, K, directly is presented which is not restricted by the particle size, shape and density. The effective dielectric Constant of the medium is evaluated from the mean bistatic scattered fields of a cluster of the random medium confined in a geometrical boundary. In this approach, the mean scattered fields are fitted to the bistatic scattered fields of a homogeneous lossy material having the same geometrical boundary. The bistatic measurement technique is based on a novel technique where only a monostatic radar and a rotatable ground plane are needed.
George Goussetis - One of the best experts on this subject based on the ideXlab platform.
-
planar leaky wave antenna with flexible control of the complex Propagation Constant
IEEE Transactions on Antennas and Propagation, 2012Co-Authors: Alejandro Javier Martinezros, Jose Luis Gomeztornero, George GoussetisAbstract:This communication demonstrates for the first time the capability to independently control the real and imaginary parts of the complex Propagation Constant in planar, printed circuit board compatible leaky-wave antennas. The structure is based on a half-mode microstrip line which is loaded with an additional row of periodic metallic posts, resulting in a substrate integrated waveguide SIW with one of its lateral electric walls replaced by a partially reflective wall. The radiation mechanism is similar to the conventional microstrip leaky-wave antenna operating in its first higher-order mode, with the novelty that the leaky-mode leakage rate can be controlled by virtue of a sparse row of metallic vias. For this topology it is demonstrated that it is possible to independently control the antenna pointing angle and main lobe beamwidth while achieving high radiation efficiencies, thus providing low-cost, low-profile, simply fed, and easily integrable leaky-wave solutions for high-gain frequency beam-scanning applications. Several prototypes operating at 15 GHz have been designed, simulated, manufactured and tested, to show the operation principle and design flexibility of this one dimensional leaky-wave antenna.
H. Johkawa - One of the best experts on this subject based on the ideXlab platform.
-
Direct measurement of Propagation Constant in optical waveguides by heterodyne scattering detection (HSD) method
IEEE Photonics Technology Letters, 1995Co-Authors: Y. Kokubun, H. JohkawaAbstract:A new measurement method for the Propagation Constant of optical waveguides, which can measure the phase difference of two distant points nondestructively, was proposed and demonstrated. A super-fine fiber probe for the photon STM is used to pick up the scattered light from an optical waveguide, and the collected light is detected using a heterodyne technique. The phase difference between two points is measured from the phase change of the electrical signal of heterodyne detection as the fiber probe traces the waveguide pattern. The phase difference between 100 μm distant points in a three-dimensional ARROW was successfully measured and the error was evaluated to be 0.25% by comparison with the theoretical value.
Chongqing Jiao - One of the best experts on this subject based on the ideXlab platform.
-
effect of the lossy layer thickness of metal cylindrical waveguide wall on the Propagation Constant of electromagnetic modes
Applied Physics Letters, 2006Co-Authors: Chongqing JiaoAbstract:Based on the dispersion equation of electromagnetic mode, the Propagation problem in a lossy cylindrical waveguide is studied. The analytic formula of Propagation Constant for any mode in the waveguide is presented, which includes the effect of the lossy layer thickness on the waveguide wall. The analysis with the analytic formula shows that the lossy layer thickness has great effect on the Propagation Constant when the thickness is 1.5 times smaller than the skin depth of good conductor (δ).
