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The field distributions of various modes in rectangular waveguides filled with uniaxial media are presented. The presented cases include aligned cases when the optic axis is parallel to one of the coordinate axes and the tilted cases when the optic axis is not parallel to any of the coordinate axes but still lies within one of the two side-wall planes. In the aligned uniaxial-z case the analytical...
Manipulating ultraviolet light presents unique challenges in technology. Here we demonstrate circular polarization selection at ultraviolet wavelengths over subwavelength distances using a flat-optical device consisting of Al chiral nanospirals periodically patterned on a glass substrate.
Computational results of the cutoff frequencies of the hybrid modes in a rectangular waveguide filled with the uniaxial medium are presented. The optic axis orientation of the inserted uniaxial medium is tilted from any of the coordinate axes but lying in one of the sidewall planes of the rectangular waveguide. The calculated results not only show the changes of the cutoff frequency of the lowest...
This paper presents a novel quasi-Yagi antenna (QYA) design in which the conventional PEC reflectors are replaced by metaedges, one-dimensional artificial perfect-magnetic-conductor-like edges. The unique reflection property of the metaedge helps miniaturize overall dimensions of the QYAs while maintaining high-gain performances. We demonstrate that the separation between the radiators and the reflectors...
A novel negative-resistance composite right/left-handed (NR-CRLH) leaky-wave antenna (LWA) is presented. The conventional CRLH unit cell is made configurable by using the negative resistance (NR) circuit. An LWA constituted by the proposed unit cells allows manipulation of the current distributions over the radiating surface of the antenna. Consequently, the radiation pattern, and directivity can...
We propose an analytic method for plasmonic filter design, freeing the design process from time-consuming FDTD simulations. We demonstrate the utility of the design model by constructing a prototype 3D plasmonic directional light sensor.
Solutions of a metallic rectangular waveguide filled with uniaxial medium are obtained with a new approach. The direction of the optic axis is tilted but lying in one of the sidewall planes of the waveguide. The formulation is based on decomposition into ordinary and extraordinary waves. The proposed method seeks wavenumbers of supported travelling modes, and is also able to calculate both cutoff...
Unified-FFT (UFFT) is a novel 3D-Planar Method of Moments (MoM) solver of the Electric Field Integral Equation (EFIE). UFFT is the resultant algorithm of combining the FFT-enhanced Matrix Solve Operations (MSO) currently utilized in Sonnet Suites with FFT-enhanced Matrix Fill Operations (MFO). It has been shown, in conjunction with iterative MSO based on GMRES, to solve matrix vector products scaling...
A rectangular waveguide filled with uniaxial medium is treated. Different orientations of the optic axis are considered. Results of wave decompositions with respect to the optic axis are presented and compared with conventional transverse-to-z solutions. Computations show that the effect of anisotropy not only changes the field distributions, but also leads to changes of dominant modes in the waveguide.
Rectangular patch antennas are modeled using arbitrarily oriented biaxially anisotropic substrates. The Method of Moments is used to compute induced currents and the results are used to calculate input impedance, resonant length, impedance bandwidth and radiation patterns. We show that the biaxial anisotropy and orientation of the medium affect performance metrics.
When solving for the radiation problem of a source in the presence of layered anisotropic medium, dyadic Green's function for the region above the source point is often required. In the case when anisotropic medium involved is reciprocal, symmetry (or reciprocity) relations of the DGFs [J.W. Graham, G. F. Pettis, J. K. Lee, “Symmetrical Property of Dyadic Green's Functions for Layered Anisotropic...
When solving radiation and/or scattering problems, the Method of Moments can give wideband information by using a Model Based Parameter Estimation technique for the expansion coefficients. The parameters are obtained by computing the values of expansion coefficients and their frequency derivatives at a fixed center frequency. This requires computing the moment matrix and its frequency derivatives...
Microstrip dipole antennas are modeled using arbitrarily oriented biaxially anisotropic substrates. The Method of Moments is used to compute induced currents and the results are used to calculate input impedance, resonant length and directive gain. We show that the orientation of the medium does affect performance metrics but at varying degrees based on the strength of the biaxial anisotropy of the...
A set of general purpose two-dimensional single-field finite-difference time-domain updating equations for solving oblique incidence electromagnetic problems is derived. The traditional FDTD updating equations are based on Maxwell's curl equations whereas the single-field FDTD updating equations are based on the vector wave equation. Performance analyses of the single-field formulation in terms of...
The problem of wave reflection and transmission at the interface between an isotropic (air) medium and biaxially anisotropic medium is solved and analyzed. We observe behavior that differs from the typical behavior at an isotropic-isotropic interface. It is seen that rotating the permittivity tensor of the biaxial medium with respect to the reference coordinate system significantly affects the reflection...
Propagation and radiation of electromagnetic waves in anisotropic media are problems of great interest from both theoretical and practical points of view. For the problems of radiation and scattering from sources embedded in stratified media, one of the most powerful and elegant analyzing tools is the dyadic Green's function (DGF) technique. Many researchers have determined and utilized the DGF for...
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