Conference Agenda

In this paper, how the conductivity with spacetime variation affects electric field distribution uniformity in a circular cylindrical insulator under electromagnetic pulse excitation in the form of double exponential is investigated. The mathematical model is on the basis of an enhanced FDTD routine with the excitation being voltage or field type. Particularly, the evaluation of the conductivity of the cell in the vicinity of the surface of the insulator and the introduction of the voltage excitation in the FDTD routine are described. It is found from the FDTD results that by regulating the spacetime characteristics of the conductivity, the purpose of improving the electric field distribution uniformity in the interior of the insulator under an electromagnetic pulse can be achieved.

Electromagnetic interference (EMI) is a fundamental issue in electronic based systems, hence filter structures including surface mounted (SMT) passive components are required to ensure the reliable operation of such systems. However, these components suffer from ferroelectric- and ferromagnetic effects, therefore applying a DC bias might lead to a significantly different value in capacitance and inductance. As a result, a designated filter design may fail to suppress unwanted EMI within a specified frequency range due to changes in the filter characteristics. This paper investigates the impact of various DC bias currents on the characteristics of a PI-filter. Modeling techniques using the Kramers-Kronig relation, vector network analyzer (VNA) measurements and 3D fullwave finite element simulation are deployed to model the impact of DC biasing and the results are compared to measurements.

In this paper, a single-field finite-difference time-domain (FDTD) formulation based on the wave equation of magnetic field and the Newmark-Beta method is presented. The resulting scheme is directionally implicit, and the numerical stability condition is relaxed than that of the traditional explicit FDTD. Its relaxed stability condition, accuracy and computational time are assessed in comparison with other explicit and implicit FDTD methods. This scheme is shown to be faster than the traditional explicit FDTD, the fully implicit Crank-Nicolson FDTD and the semi-implicit mixed Newmark-leapfrog FDTD schemes.

An efficient path integral (PI) model for the accurate analysis of dielectric structures via the two-dimensional nonstandard finite-difference time-domain technique, is introduced in this paper. Based initially on the perfectly electric conductor case, which accommodates orthogonal cells at curved surfaces, the novel scheme employs the occupied ratio of dielectrics in the necessary cells, providing thus an easy means to treat several practical applications. For its verification, the proposed PI model examines the scattering from a dielectric cylinder and leads to very precise results, while, concurrently, proving its straightforward and smooth incorporation in the NS-FDTD algorithm.

The analytical expressions based on the Schelkunoff transmission line theory are commonly used to calculate the shielding effectiveness of the infinite planar shields, cylindrical shields, and spherical shields. While these analytical expressions are seen to be accurate in the case of far-field shielding where the impedance is equal to 120𝝅, its accuracy in the case of near field especially low impedance current loop field source is not insured. In this paper, the approximate expressions of low-impedance current-loop field source in analytical methods based on transmission line theory for magnetic shielding evaluation are compared. The error committed using different near-field wave impedance formulas for the shielding effectiveness calculation is revealed. An application to the optimization of a multilayer shield is proposed.

In the Finite-difference time-domain (FDTD) method, the analysis domain is divided into orthogonal meshes, the space is discretized by the finite difference method, and the time step is advanced by the Leap-frog method. Therefore, it is difficult to accurately model analysis regions with complex shapes or smooth curved surfaces, and numerical errors will occur in the computational results, suffering from sufficient numerical verification. In this study, the HE$_{11}$ mode is inputted into a corrugated waveguide, and a helical filter is set as a filter to generate an optical vortex using the FDTD method. Moreover, the empirical mode decomposition (EMD) is adopted to remove numerical errors and extract the clear physical phenomenon of the optical vortex.

Radionavigaton systems that operate in the low and medium frequency band require an accurate prediction of electromagnetic ground wave propagation delays that are caused by the finite conductivity and permittivity of the earths surface. To consider the complex pattern of the mixed land-sea propagation path in the application of the terrestrial Ranging-Mode (R-Mode) system a parallel processing software framework for the calculation of the ground wave propagation delay and the attenuation was developed. It combines existing approaches for the calculation of electromagnetic ground wave propagation with algorithms for the calculation of ground conductivity and permittivity following ITU-R recommendations. Beside R-Mode, the software framework enables the fast computation of propagation parameters for ground waves in the high, medium and low frequency band on a 2D grid.

With the advent of low-power microelectronic wireless devices, a large number of wireless sensors will be deployed in order to form a wireless network, and the frequent replacement/charging of conventional power source (battery) is inconvenient as a lot of maintenance efforts are required. Consequently, there is an urgent demand for power harvesting techniques and energy harvesters. Since radio frequency (RF) signals are abundant in the modern environment, RF energy harvesting is a feasible solution. In this regard, a new topology of a compact and broadband metasurface absorber is designed and optimized. The proposed metasurface absorber consists of a spoof local surface plasmon resonator designed on an FR4 substrate and fed by four coaxial ports. An air gap layer between the FR4 substrate and the bottom metal ground is introduced to decrease the equivalent relative permittivity of the whole dielectric layer. Four metal vias are set symmetrically on the circular ring and pass through the dielectric layer and the air gap so that the induced current on the unit can be channeled to the loads. The symmetry of the unit pattern and via position enables the metasurface to receive incoming electromagnetic waves in two linear polarization directions. To compromise different performances of the absorber, an optimization methodology using particle swarm optimization and finite element method is proposed and implemented on a prototype design with outstanding results.

This paper describes large-scale full wave analyses of electromagnetic fields by the finite element method with an iterative domain decomposition method. A stationary vector wave equation for the high-frequency electromagnetic field analyses is solved taking an electric field as an unknown function. Although this solver is capable of detailed, fast, and efficient finite element analysis of large-scale electromagnetic problems using the iterative domain decomposition method (IDDM) and the corresponding parallel distributed processing environment, it still requires a large number of iterative computation trials and computation time. In this study, we found that increasing the size of the subdomain in the IDDM improves the convergence of the accuracy of the iterative method and reduces the computation time. We are also considering replacing the solver with a subdomain solver that can handle larger subdomains.

Joule losses cannot be ignored when dealing with high-power millimeter waves. Therefore, the excitation of optical vortexes presents a challenge, in spite of their potential for utilization. Waveguides are used for long-distance transmission, and vortex modes can be represented by combining eigenmodes of different phases. Hence, if we can control the higher-order modes generated by the axial misalignment, we can excite optical vortices. As a first step toward proposing a method for the excitation of optical vortices, we calculated the coupling between the tilted Gaussian beam and the waveguide mode to be excited. In addition, angular momentum flux was also evaluated as a measure of vorticity.

This contribution investigates the connection between Isogeometric Analysis (IGA) and the Partial Element Equivalent Circuit (PEEC) method for full-wave electromagnetic problems. We demonstrate that using the spline-based geometry concepts from IGA allows for extracting circuit elements without an explicit meshing step. Moreover, the proposed IGA-PEEC method converges for complex geometries up to three times faster than the conventional PEEC approach and, in turn, it requires a significantly lower number of degrees of freedom to solve a problem with comparable accuracy. The resulting method is closely related to the isogeometric boundary element method. However, it uses lowest-order basis functions to allow for straightforward physical and circuit interpretations. The findings are validated by coaxial cable example with complex geometry, i.e., significant curvature by studying emitted fields due to incisions in the shielding.

This paper evaluates a novel solenoid coil design with a magnetic concrete core in the context of wireless power transfer. The evaluation addresses its performance and compliance with the safety levels for electromagnetic exposure. First, simulation analyses are carried out using the finite element method and then validated by realistic measurements on a prototype system built to power a lightweight autonomous shuttle bus.

The results are used to determine the shape and placement of possibly necessary shielding structures.

The growing demand for sustainable energy generation has often pointed to solar energy as a very promising alternative. A new way to harvest solar energy is through solar rectennas. These systems are the integration of micro size antennas and nano diodes. In this way, electromagnetic energy can be captured and converted to the form of direct current. The challenges for the development of this technology are due to the submicron sizes since the theory that describes the operation of antennas moves away from classical electromagnetic behavior and incorporates quantum effects. At the same time, diodes operating in tens or hundreds of THz need specific properties. Within this context, this work presents an investigative study on solar rectennas for operation in THz range by using a bowtie antenna and a geometric diode, both based on graphene.

We propose to compute highly resonant electromagnetic devices’ spectral properties, i.e., Q-values and resonance frequencies, by using a convoluted radial basis function neural network. Working in the time domain we define an activation function for the network and perform a convolution between its output and the excitation signal. This enables fitting and extrapolating the time signal using a low number of training data, which, in the end, may result in a faster computation of those parameters when compared to usual methods. In order to demonstrate our approach, we compute the spectral estimation of a highly resonant filter’s output.