Electrostatic theory of rectangular waveguides filled with anisotropic media

The electrostatic (or, in a better word, quasi-electrostatic) theory of waves propagation in a long, rectangular waveguide having perfect electric conductor walls that filled with an anisotropic medium (here, a medium of nanowire-based hyperbolic metamaterials) is presented. Some data on characteristics of these waves are prepared. The presented results include electrostatic field configurations (modes) that can be supported by such structures and their corresponding cutoff frequencies, group velocities, power flows and storage energies.

SAR Image Simulation of Complex Target Including Multiple Scattering

We present a GPU-based computation for simulating the synthetic aperture radar (SAR) image of the complex target. To be more realistic, we included the multiple scattering field and antenna pattern tracking in producing the SAR echo signal for both Stripmap and Spotlight modes. Of the signal chains, the computation of the backscattering field is the most computationally intensive. To resolve the issue, we implement a computation parallelization for SAR echo signal generation. By profiling, the overall processing was identified to find which is the heavy loading stage. To further accommodate the hardware structure, we made extensive modifications in the CUDA kernel function. As a result, the computation efficiency is much improved, with over 224 times the speed up. The computation complexity by comparing the CPU and GPU computations was provided. We validated the proposed simulation algorithm using canonical targets, including a perfectly electric conductor (PEC), dielectric spheres, and rotated/unrotated dihedral corner reflectors. Additionally, the targets can be a multi-layered dielectric coating or a layered medium. The latter case aimed to evaluate the polarimetric response quantitively. Then, we simulated a complex target with various poses relative to the SAR imaging geometry. We show that the simulated images have high fidelity in geometric and radiometric specifications. The decomposition of images from individual scattering bounce offers valuable exploitation of the scattering mechanisms responsible for imaging certain target features.

The Distribution of the Thermal Field in an Elliptical Electric Conductor Coated with Insulation

The paper determines the stationary thermal field in an elliptical cross-section electric conductor coated with insulation. Heat is generated by the flow of alternating current (AC) through the conducting core, and then dissipated from the insulation surface via convection and radiation. The authors have developed an original method for hybrid (analytical–numerical) modeling of a field. This method has been used to solve the relevant boundary problem of Poisson’s equation. While the eigenfunctions of the Laplace operator were determined analytically, the coefficients of the eigenfunctions were calculated by iteratively solving an appropriate system of algebraic equations. The proposed method enables the analysis of systems with an elliptical geometry and a heterogeneous layered structure (e.g., air, aluminum alloy, PCV), and does not require area discretization (grid). The developed analytical–numerical (AN) method has been positively verified using finite elements (FEs). The determined thermal field is illustrated graphically. The obtained solution has a good physical interpretation.

Modified Theory of Physical Optics Approach to Diffraction by an Interface between PEMC and Absorbing Half-Planes

The scattering of electromagnetic plane waves by an interface, located between perfect electromagnetic conductor and absorbing half-planes is investigated. The perfect electromagnetic conductor half-plane is divided into perfect electric conductor and perfect magnetic conductor half-screens. The same decomposition is done for the absorbing surface. Then four separate geometries are defined according to this approach. The scattered fields by the four sub-problems are obtained with the aid of the modified theory of physical optics. The resultant scattering integrals are combined in a single expression by using key formulas, defined for the perfect electromagnetic conductor and absorbing surfaces. The scattering integral is asymptotically evaluated for large values of the wave-number and the diffracted and geometric optics fields are obtained. The behaviors of the derived field expressions are analyzed numerically.

A Modified Hybrid Integral Equation to Electromagnetic Scattering from Composite PEC-Dielectric Objects Containing Closed-Open PEC Junctions

To efficiently analyze the electromagnetic scattering from composite perfect electric conductor (PEC)-dielectric objects with coexisting closed-open PEC junctions, a modified hybrid integral equation (HIE) is established as the surface integral equation (SIE) part of the volume surface integral equation (VSIE), which employs the combined field integral equation (CFIE) and the electric field integral equation (EFIE) on the closed and open PEC surfaces, respectively. Different from the traditional HIE modeled for the objects whose closed and open PEC surfaces are strictly separate, the modified HIE can be applied to the objects containing closed-open junctions. A matrix equation is obtained by using the Galerkin’s method of moments (MoM), which is augmented with the spherical harmonics expansion-based multilevel fast multipole algorithm (SE-MLFMA), improved by the mixed-potential representation and the triangle/tetrahedron-based grouping scheme. Because in the improved SE-MLFMA, the memory usage for storing the radiation patterns of basis functions is independent of the SIE type in the VSIE, it is highly appropriate for the fast solution of the VSIE that contains the HIE. Various numerical experiments demonstrate that during the calculation of composite objects containing closed-open PEC junctions, the application of the modified HIE in the VSIE can give reliable results with fast convergence speed.

Compact and Robust Fabry-Perot Cavity Antenna with PEC Wall

In this paper, a novel Fabry-Perot cavity (FPC) antenna with a perfect electric conductor (PEC) wall is proposed to design a structurally compact and robust high-gain antenna. Generally, the FPC antenna comprising a PEC ground and a partially reflective dielectric surface (PRDS) is required to have a half-wavelength height to satisfy the resonance condition. If a perfect magnetic conductor (PMC) is substituted for the PEC ground, the height of the FPC antenna can be reduced to a quarter wavelength. The PRDS of the proposed FPC antenna is located on the PEC ground to obtain the effect of a PMC. Moreover, PEC walls are employed to block leakage by a guided mode inside the PRDS. As a result, the proposed FPC antenna can be designed as a compact high-gain antenna although it is composed of PEC ground and PRDS. To verify its feasibility, we simulated and measured the performance of the proposed antenna regarding the reflection coefficient, peak gain, and far-field radiation pattern. Finally, the height of the proposed antenna was reduced by approximately 50% compared with the conventional antenna, while the peak gain is more than equal to that of the conventional antenna.

Effects of the FR 4 Substrate Realized in a Circularly Polarized UHF-RFID Reader Antenna with Fractal Geometry for Enhancing Parameters

The proposed RFID reader antenna progressed with perfect electric conductor (PEC) as the radiating element and FR 4 as the substrate to achieve circular polarization, enhancement in bandwidth, and read range. The design presents a CPW feed RFID antenna for near-field reading applications, between the range of 903 MHz to 929 MHz. The operating frequency of the proposed design is 900 MHz, axial ratio of the model is less than 3 dB, impedance bandwidth is 256 MHz, and axial bandwidth is 36 MHz, proving to be adequate for near-field RFID reader applications such as item-level tagging and smart shelf. The proposed antenna model is realized with fractal structure to achieve miniaturization. The developed antenna is optimized using EM software for numerical analysis. The designed antenna is fabricated, and the prototype is characterized in terms of dielectric constant and loss tangent. The obtained results indicate high correlation with simulation results.

Finite-Difference Time-Domain Simulations

This work discusses the Finite-Difference Time-Domain (FDTD) technique to simulate an electromagnetic wave assuming one, two and three dimensions. The propagation medium is assumed to be a free space bounded by two absorbing boundaries, perfect matched layer (PML) and perfect electric conductor (PEC). The FDTD-1D is considered in free space while FDTD-2D and 3D are considered both in free space and in a free space-medium consisting of dielectric sphere and cylinder in the center. In this case, we model the incident and the scattered electromagnetic fields reflected back from hitting the dielectric cylinder and sphere. Moreover, the simulation starts by generating an electromagnetic pulse either in the middle or at one end of the medium and this pulse can be either Gaussian or sinusoidal. For the FDTD-3D, an antenna dipole is assumed to be the source generator of the electromagnetic pulse. We also provide the analytic solutions to confirm the accuracy of the FDTD technique.