Session: TU3E | Novel structures, Effects, and Techniques |
Chair: | Tapan K. Sarkar, Syracuse University |
Co-Chair: | Silvio E. Barbin, University of Sao Paulo |
Abstract: | The session gathers papers contributing the novel field theory techniques applied to various problems. Firstly a bulk multilayer mushroom-type metamaterial is presented showing a negative refraction in a wide frequency band, modeled using a homogenization method. Newly designed photonic choke joints for dual-polarization waveguides of a rectangular cross-section provide a contactless low loss connection. Scattering parameters and equivalent circuit for a slot cutting a microstrip line are determined by a full wave method in the next paper. Further heat generated inside water due to propagation of microwave pulses is calculated by the finite difference time domain method. An algorithm for the detection of electrically small scatterers in a known background medium is finally presented. |
| | TU3E-1 | Broadband Negative Refraction at Microwaves with a Multilayered Mushroom-Type Metamaterial |
1:20 PM-1:40 PM | A. B. Yakovlev1, M. G. Silveirinha2, C. S. Kaipa1, 1University of Mississippi, University, United States, 2University of Coimbra - Instituto de Telecommunicações, Coimbra, Portugal |
(1476) | In this paper, a multilayered mushroom-type structure is proposed as a bulk metamaterial, which creates a broadband negative refraction. The metamaterial is modeled using homogenization methods as a multilayered structure formed by a uniaxial wire medium loaded with periodic metallic elements (for example, patch arrays). It is shown that the phase of transmission coefficient decreases with the increasing incidence angle, resulting in the negative spatial shift of the transmitted wave. The homogenization model results are obtained with the uniform plane-wave incidence, and the full-wave CST results are generated with a Gaussian beam excitation, showing a strong negative refraction in a wide frequency band. |
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TU3E-2 | Photonic Choke-Joints for Dual-Polarization Waveguides |
1:40 PM-2:00 PM | E. J. Wollack, K. U-yen, D. T. Chuss, NASA Goddard Space Flight Center, Greenbelt, United States |
(1765) | Two photonic choke joint (PCJ) structures for dual-polarization waveguides have been investigated. Structures with Cartesian and Archimedean tiling were implemented to provide a low-loss non-contacting surface at a waveguide interface while preserving the signal polarizations. The optimal dimensions for each tiling configuration have been determined. For each of these schemes the experimental results for structures with a finite tiling provide near ideal transmission and reflection performance over the full waveguide band. |
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TU3E-3 | High-Frequency Scattering by a Narrow Gap on a Microstrip Line |
2:00 PM-2:20 PM | R. R. Berral1, F. Mesa1, D. R. Jackson 2, 1University of Seville, Seville, Spain, 2University of Houston, Houston, United States |
(1608) | The high-frequency scattering parameters and equivalent circuit for a gap on a microstrip line are found by analyzing the problem with an accurate semi-analytical method in the spectral domain, using an even/odd mode analysis. The analysis accounts for radiation into space as well as into surface waves, both of which become more pronounced at higher frequencies. The analysis allows for an examination of these two separate powers in order to examine the power loss mechanism at the gap. The results remain accurate even at high frequencies where the characteristic impedance of the microstrip line becomes non-unique. The only assumption is that the length of the gap is fairly small compared to a wavelength. |
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TU3E-4 | Heat Distribution Pattern of Double Brillouin Pulse Inside Water |
2:20 PM-2:40 PM | B. Montazeri Najafabadi, R. Safian, Isfahan university of technology, Isfahan, Iran |
(1295) | In a dispersive medium excited by a wideband pulse, the appearance of the steady-state part of the propagated signal is preceded by oscillations known as precursors. Precursor fields in lossy Debye media have been shown to present a subexponential attenuation rate, thus becoming good candidates for applications requiring field penetration into such media. This paper aims to study the performance of a pulse consisting of two mutually delayed precursors for microwave heating. A comparison between this particular pulse and a general excitation, modulated rectangular pulse, will be presented. Finite difference time domain simulations under a specific algorithm for calculation of temperature distribution pattern of microwave heating are employed to evaluate the performance of precursorbased excitation and to compare it with modulated rectangular pulse. |
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TU3E-5 | Detection at Microwave Frequencies Based on Self-Adjoint Sensitivity Analysis |
2:40 PM-3:00 PM | L. Liu, A. Trehan, N. K. Nikolova, McMaster University, Hamilton, Canada |
(1650) | A novel general formulation of the response sensitivity analysis is proposed and implemented in a computationally efficient algorithm for the detection of electrically small scatterers in a known background medium. The responses of the background medium where no scatterers are present are modeled via ultra-wideband time-domain simulation. Using these modeled responses and the measured responses of the examined object, 3D derivative maps are obtained within the object’s volume. The minima or maxima in these maps indicate the locations where the voxel permittivities and conductivities differ significantly between the measured and modeled media. Localization of the scatterers in a complex heterogeneous example is successfully conducted. The limitations of the detection algorithm and its resolution are studied using a homogeneous background example in terms of the number of transmission/reception points, the dielectric contrast and the size of the scatterer. |
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