3D Full-wave Simulation Research Articles

Terahertz magnetoplasmon resonances in coupled cavities formed in a gated two-dimensional electron gas.

We report on both experiments and theory of low-terahertz frequency range (up to 400 GHz) magnetoplasmons in a gated two-dimensional electron gas at low (<4K) temperatures. The evolution of magnetoplasmon resonances was observed as a function of magnetic field at frequencies up to ∼400 GHz. Full-wave 3D simulations of the system predicted the spatial distribution of plasmon modes in the 2D channel, along with their frequency response, allowing us to distinguish those resonances caused by bulk and edge magnetoplasmons in the experiments. Our methodology is anticipated to be applicable to the low temperature (<4K) on-chip terahertz measurements of a wide range of other low-dimensional mesoscopic systems.

Energy and Communication Efficient FSS for Equivalent Model of Hard-Coated Energy Saving Glass

An energy and communication efficient FSS is presented for equivalent model of ESG with hard coating. An FSS with second order band-pass response has been realized by full wave 3D simulations and results have been imitated using an equivalent circuit model to calculate the value of lumped elements. The design is composed of three cascaded FSSs with two glass layers of 6 mm each in between. Due to this topology the transmission of useful RF/microwave signals has been improved for a wider bandwidth, increased thermal insulation, stable frequency and polarization at oblique incidence and security for WLAN at 2.45 GHz.

Head‐only21MHzradiofrequency exposure system design and implementation

In this work a 21 MHz radiofrequency (RF) exposure system was designed, constructed and evaluated as a testing platform for MRI device safety. The exposure system consisted of a birdcage coil powered in quadrature by a power system consisting of a hybrid coupler, a power splitter, a phase shifter and two baluns. The birdcage coil was designed as a low-pass 16 rung coil. Both the coil and the power system were fabricated as printed circuit boards with a copper thickness of 205.7 μm and a G10 substrate thickness of 581.7 μm. The birdcage was assembled by wrapping the copper clad G10 inside of an acrylic tube. A shield for the coil was created as a cylindrical ground plane with a diameter of 39.7 cm. The birdcage and the power system were simulated in ADS and EMPro, Keysight Technologies Inc. both as lumped elements and using full wave 3D simulations. Simulation results were compared to measurements of the produced components to validate each component and entire system. In addition, a 3D magnetic field probe was developed to measure and compare the fields to analytical and numerical calculations.

Planar Sensor for Material Characterization Based on the Sierpinski Fractal Curve

This paper presents a planar and compact microwave resonator sensor to characterize materials. The geometry of the resonator is based on the Sierpinski fractal curve and has four poles in the frequency range from 0.5 GHz to 5.5 GHz. Any of the four poles can be used to measure samples with low permittivity values, where the first pole is suitable for samples with high permittivity values. The sensitivity of the poles and return losses of the sensor are presented and obtained using a full-wave 3D simulator software. The device is manufactured and validated through a comparison between simulated and measured results.

Near-Field Scanning-Based Shielding Effectiveness Extraction for Board-Level Shielding Cans

The conventional definition of shielding effectiveness (SE) is well suited for calculations of far-field electromagnetic shielding. However, in the near field, SE calculations are not as straightforward. In radio-frequency interference (RFI) problems, the majority of field coupling occurs in the near field. Thus, a well-defined method for calculating the near-field SE is needed to estimate the suppression of RFI achieved by shielding cans. In this study, a method based on near-field scanning is developed to extract the SE of board-level shielding cans. The SE is defined by modeling the shielded noise source as equivalent dipole moments. The accuracy of the equivalent source is analyzed via the least-square error and correlation coefficient as confidence verification parameters. By applying the reciprocity theorem, the voltage coupled on a planar inverted F antenna from an unshielded and a shielded source is calculated. The coupled voltage from a shielded noise source serves as a reference to validate the effectiveness of the proposed method. Practical shielding cans were used to develop and validate the SE extraction method using full-wave 3D simulations and measurements.

On the computation and comparison of specific absorption rate (SAR) in a skin tissue using analytical and numerical methods

AbstractSpecific absorption rate (SAR) is a measure of safety and a requirement for portable radio frequency devices which are regulated mainly by the standards recommended by the Institute of Electrical and Electronics Engineers (IEEE) and International Commission on Non‐Ionizing Radiation Protection (ICNIRP). Accurate approximation of SAR is therefore important for safety as well as for compliance purposes. This article presents the analytical representation and derivation of the SAR from the basics of electromagnetic theory, Maxwell Equations, and law of conservation of energy in electromagnetic theory. It is shown, analytically, that for a time harmonic electromagnetic wave propagating in a homogeneous lossy medium having permittivity ϵ, permeability µ, and conductivity σ, the time rate change of electric and magnetic energy densities at steady state inside a given volume is zero. It is also shown that at the steady state, the net power flowing through a volume, bounded by a surface is equal to the power dissipated in that volume. Furthermore, this work demonstrates that at the steady state, SAR can be represented in terms of power density or in terms of power dissipated in the given volume. Moreover, calculation of SAR for a 1 mm × 1 mm × 0.01 m box having the dielectric properties of human skin was performed using the derived formulas and then compared with the numerical results, obtained using a full wave 3D simulation tool, HFSS. A good agreement was found between the analytical and numerical results.

Mie calculation of electromagnetic near-field for a multilayered sphere

We have developed an algorithm to calculate electric and magnetic fields inside and around a multilayered sphere. The algorithm includes explicit expressions for Mie expansion coefficients inside the sphere and calculation of the vector spherical harmonics in terms of the Riccati–Bessel functions and their logarithmic derivatives. This novel approach has been implemented in the new version of our program scattnlay. Scattnlay 2.0 will be the first publicly available (at GitHub, https://github.com/ovidiopr/scattnlay) program, based on the Mie theory, which can calculate near-fields for the general case of a multilayer sphere. Several tests were designed to verify that the results obtained with our code match literature results and those obtained through similar programs (limited to core-shell structures) or full-wave 3D simulations. These tests demonstrate that the implementation is effective, yielding accurate values of electric and magnetic fields for a wide range of size parameters, number of layers, and refractive indices. Program summaryProgram title: scattnlay 2.0Catalogue identifier: AEEY_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEY_v2_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: GNU GPL v3No. of lines in distributed program, including test data, etc.: 34502No. of bytes in distributed program, including test data, etc.: 851543Distribution format: tar.gzProgramming language: C++11.Computer: Any computer with a C++11 compiler.Operating system: Linux (any version), Windows, Solaris.RAM: 1 Mb–100 MbClassification: 1.3.Does the new version supersede the previous version?: YesNature of problem: The scattering of electromagnetic (EM) radiation by a multilayered sphere is an interesting phenomenon which has recently drawn a great attention for application of tailor-made nanostructures in several fields like medicine (optical imaging and photothermal cancer therapy), atmospheric sciences (to study light absorption by aerosols), design of invisibility cloaks, etc. Expressions of scattering coefficients seem to be simple and straightforward to implement; however, they involve several numerical difficulties that make most of the existent algorithms inapplicable to several common cases. An improved recursive algorithm that circumvents most of the numerical problems present in previous algorithms has been developed by Yang [1]. This algorithm has been implemented in our program [2] to calculate the far-field parameters. In the updated version we have developed and implemented an efficient algorithm for the calculation of electric and magnetic fields inside and around multilayered spheres. In addition to the near-field calculations, the program includes some new functionalities, such as the possibility of including a layer composed of a perfect electrical conductor.Solution method: Calculation of Mie scattering coefficients and efficiency factors for a multilayered sphere as described by Yang [1], combined with standard solutions of the scattering amplitude functions. Determination of electric and magnetic fields using an algorithm developed in this work.Reasons for new version: To include calculations of electric and magnetic fields inside and around the particle.Summary of revisions: The code has been ported to C++11, which has given a cleaner and faster implementation. A new algorithm has been devised and implemented to include the calculation of near electric and magnetic fields. Finally, several small bug fixes and improvements to the original code have been made.Restrictions: Single scattering and permeability of the layers fixed to unity. Large complex part of layers refractive index leads to convergence problems.Running time: Seconds to minutes

Dual applicator thermal ablation at 2.45 GHz: a numerical comparison and experiments on synchronous versus asynchronous and switched-mode feeding

Purpose: This paper compares the results obtained with numerical simulations and ex vivo experiments involving a dual applicator microwave thermal ablation system operating at a 2.45 GHz frequency, both in synchronous and asynchronous modes. Our purpose was to demonstrate that at this frequency an asynchronous or switched-mode system performs essentially as well as the synchronous one, in spite of the prevailing belief that coherence would assure better thermal (TH) synergy. Numerical analysis: The calculations of temperature fields were based on the Pennes bioheat equation, taking into account the effects of blood perfusion by means of a full-wave 3D simulator that allows numerical electromagnetic (EM) and TH analyses. Materials and methods: Experiments were done using a 100 W microwave (MW) power generator and a fast switched-mode sequential ‘active’ power splitter. By adding a further passive power splitter we arranged a test bed for an accurate experimental comparison of synchronous versus switched-mode TH ablations. Results: The experimental ablation zones produced by a dual applicator array on ex vivo swine tissue corresponded well with the simulated ones, confirming that the simplifications assumed in the full-wave analysis were compatible with the aim of our work. Conclusions: Numerical simulations and experiments show that at a 2.45 GHz industrial, scientific and medical (ISM) frequency, synchronous, asynchronous and switched-mode multi-probe systems are substantially equivalent in terms of ablative performance. Moreover, the switched-mode solution offers simpler operation along with lesser sensitivity to the placement of applicators in the tissue.

Linking circuit simulation with full-wave solver for board-level EMC design

In the fast paced electronics world, simulation has become an indispensable tool for every designer in recent years. In this paper, we present a guide to setting up a coupled simulation method from a SPICE-like circuit simulation and a full wave 3D simulation. This coupling offers the possibility to calculate the field distribution in a structure considering the effects of an attached circuit by applying the superposition theorem. As long as only elements on the circuit are modified, it allows fields to be calculated at the speed of a circuit simulation. The paper contains an introduction to the properties of time and frequency domain 3D solvers, discussing their effectiveness for different applications. In the main part of the paper we deal with the definition of ports in the 3D and circuit as the set-up of a coupled model needs special attention to the ground concept. Finally, the method is applied to the simulation of radiated and conducted emission on a realistic PCB.

EMI Prediction of Slew-Rate Controlled I/O Buffers by Full-Wave and Circuit Co-Simulation

In this paper, a modeling and co-simulation methodology is proposed to predict the radiated electromagnetic interference (EMI) from on-chip switching I/O buffers. The output waveforms of I/O buffers are simulated including the on-chip I/O buffer circuit and the RC extracted on-chip interconnect netlist, package, and printed circuit board (PCB). In order to accurately estimate the EMI, a full-wave 3D simulation is performed including the measurement environment. The simulation results are compared with near-field electromagnetic scan results and farfield measurements from an anechoic chamber, and the sources of emission peaks were analyzed. For accurate far-field EMI simulation, PCB power trace models considering IC switching current paths and external power cable models must be considered for accurate EMI prediction. With the proposed EMI simulation model and flow, the electromagnetic compatibility can be tested even before the IC is

Absorption Enhancement in Solution Processed Metal-Semiconductor Nanocomposites

We present a full wave 3D simulation study of optical absorption enhancement in solution processed metal-semiconductor nanocomposite ultrathin films, which consist of colloidal metallic nanoparticles (MNPs) and semiconductor matrices of polymer and colloidal quantum dots (CQD). We present an approach for modeling the optical properties of a CQD film, and study the effect of the optical properties of the semiconductor in the near field enhancement showing that CQD is a very promising platform to exploit the benefits of the near-field effects. We show that over a 100% enhancement can be achieved in the visible-near infrared region of the spectrum for CQD PbS films, with a maximum gain factor of 4 when MNPs are on resonance. We study in detail the effect of MNP capping for different ligand lengths and materials and propose solutions to optimize absorption enhancement.

NEGATIVE REFRACTIVE INDEX BEHAVIOR THROUGH MAGNETO-ELECTRIC COUPLING IN SPLIT RING RESONATORS

An investigation on the possibility of obtaining a negative refractive index behavior in split ring resonators (SRRs) through magneto-electric coupling is presented. We have performed rigorous electromagnetic simulations using a full-wave 3D simulator, and the obtained results have been verifled by our experimental realizations and measurements. The results conflrm that the increase of magneto- electric gyrotropic activity inside a bi-anistropic medium can lead to the establishment of backward-wave propagation.