Numerical Electromagnetic Modeling Research Articles

The 2023 IEEE Microwave Theory and Technology Society International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization [Conference Report

The 2023 IEEE Microwave Theory and Technology Society International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization [Conference Report

IEEE Society Interaction, Industry Engagement, and Young Professionals Are the Future of the MTT-S [President’s Column

From my perspective in June 2023, the IEEE Microwave Theory and Technology Society (MTT-S) is a vibrant Society, with many activities ongoing related to our technical field. Several conferences have occurred with a significant impact on our members; those include the International Microwave and Antenna Symposium (IMAS), in Cairo, Egypt ( <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1</xref> ); the IEEE Wireless and Microwave Technology Conference, in Florida, USA; the IEEE Texas Symposium on Wireless and Microwave Circuits and Systems, in Texas, USA; the IEEE MTT-S International Wireless Symposium, in Qingdao, China; and the IEEE Workshop on Signal and Power Integrity, in Aveiro, Portugal. For June, we have an entire month of events, including the brand-new Wireless Power Transfer and Exhibition, in San Diego, CA, USA; the IEEE RF Radio Frequency Integrated Circuits Symposium; our flagship conference, the IEEE MTT-S International Microwave Symposium; and the Automatic Radio Frequency Techniques Group Microwave Measurement Conference, all co-located in San Diego. At the end of the month, the International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization will be held in Winnipeg, MB, Canada. At all these events, we have a vibrant number of Young Professionals (YPs) events planned along with our industry colleagues, creating an excellent opportunity for academic, industry, and government interaction, impacting the future of microwaves and technology worldwide.

Design and Simulation of a Square Loop Antenna for 920 MHz

This study describes design and simulation of a loop antenna. A square loop antenna is designed for 920 MHz. The loop antenna is then modelled and simulated using 4NEC2 electromagnetic (EM) modeling software. 4NEC2 is a completely free numerical electromagnetic modeling code. It is based on method of moments technique to solve electromagnetic boundary value problem. The 4NEC2 simulation of the loop antenna design predicted antenna resonant frequency to be 920 MHz, Return Loss bandwidth of 130 MHz and input impedance of 50.14 -j0.30 Ohm. The antenna radiation pattern is then simulated at 920 MHz. The Return Loss, VSWR, Input Impedance and Radiation Pattern of the antenna predicated by 4NEC2 simulation are studied for the possible development of copper or aluminium tube based loop antenna.

The IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization 2022

The IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization 2022

Embrace the Change Together: WiM Event at NEMO 2020 [Women in Microwaves

Reports on the MMTS society's International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO 2020) that was held in Hangzhou, China, from 7 to 9 December 2020.

Guest Editorial

The International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) has emerged as a unique annual forum in the fields of electromagnetic- and multiphysics-based modeling, simulation, and optimization for RF, microwave, terahertz, and other applications. Founded in 2014 by the IEEE Microwave Theory and Techniques Society (MTT-S) and with the aim of stimulating a broad exploration and discussion of “disruptive” technologies of EM-CAD in addition to traditional topics, the sixth edition of this three-continent-rotational conference, NEMO2019, took place in Cambridge, MA, USA, in May 29–31, just before the International Microwave Symposium (IMS) which was also held in Boston, MA, USA.

Design and Sensitivity Analysis of EBG Stripline Common-Mode Filters

Workflow of electromagnetic bandgap (EBG) common-mode (CM) filter design of edge-coupled differential pairs on a printed circuit board (PCB) and sensitivity of its characteristics to variations of geometrical and material parameters are discussed. A number of simple 20-GHz EBG CM notch filters for differential stripline pairs are designed using full-wave numerical electromagnetic modeling, fabricating, and testing. The cases of one and two stripline differential pairs crossing the EBG patches are considered. The modeled and measured mixed-mode S -parameters are analyzed as functions of geometrical parameters, including size and number of EBG patches, gaps between them, geometry and position of signal traces across the EBG patches, and thicknesses of dielectric layers. The agreement between the measured and modeled mixed-mode S- parameters validates the models and allows for further numerical experiments. It is shown that the EBG filter performance depends on various subtle technological features, e.g., conductor surface roughness on metal surfaces; length imbalance on a differential pair; rate of coupling of lines within each differential pair and between the pairs; and some other factors. The systematic analysis of the trends for filter characteristics as functions of various design parameters allows for an optimal design of the CM notch filter.

Novel techniques for numerically efficient solution of multiscale problems in computational electromagnetics

AbstractMultiscale problems in numerical electromagnetics are becoming increasingly common with the advent and widespread usage of compact mobile phones, body area networks, small and nano antennas, sensors, high‐speed interconnects, integrated circuits, and complex electronic packaging structures, to name just a few commercial applications. Numerical electromagnetic modeling and simulation of structures with multiscale features are highly challenging due to the fact that electrically small as well as large features are simultaneously present in the model that demands for discretization of the computational domain such that the number of degrees of freedom is very large, thus levying a heavy burden on the computational resources. The multiscale nature of a given problem also exacerbates the challenge of generating very fine meshes that do not introduce instabilities or ill‐conditioned behaviors.In this paper, we present novel techniques for an efficient solution of multiscale problems in the time‐domain. The proposed techniques handle arbitrarily shaped objects with fine features by using the dipole moment–based method of moments (MoM) type formulation in the MoM domain and electrically large objects in the finite‐difference time‐domain (FDTD) domain. Scattered fields in the MoM domain are obtained in closed forms and directly in the time‐domain at the desired observation points on a planar interface, which are combined with the conventional FDTD update equations. The time‐domain scattered fields computed by using the MoM formulations presented herein are stable in their implementation.

A Coaxial RF Applicator for Ultra-High Field Human MRI.

To develop a novel radio-frequency (RF) concept for ultra-high field (UHF) human magnetic resonance imaging (MRI) based on a coaxial resonant cavity. A two-channel slotted coaxial cavity RF applicator was designed for human head MRI at 9.4T. Physical dimensions made the proposed conducting structure resonant at the required frequency without tuning lumped elements. Numerical electromagnetic modeling was used to optimize the design. RF safety was assessed with two representative human body models. MR experiments on a 9.4T scanner included gradient echo images and mapping of a circularly polarized RF magnetic field in the human head phantom. The simulations and the phantom MR experiments agreed both qualitatively and quantitatively. The design was relatively simple, robust and required only a few additional reactive elements for the applicator's input impedance matching. The transmit efficiency and homogeneity of the excitation field were only 20% and 4% lower compared to a conventional 8-channel head array. The coaxial RF applicator was feasible for human MRI at UHF and required no lumped elements for its tuning. Imaging performance of the RF applicator was only moderately lower compared to the conventional transmit array, but would be sufficient to provide an anatomical reference for the heteronuclei MRI. An alternative approach with the minimal involvement of lumped elements becomes feasible to design volume-type RF coils for UHF human MRI.

Decoupling of a double‐row 16‐element tight‐fit transceiver phased array for human whole‐brain imaging at 9.4 T

One of the major challenges in constructing multi-channel and multi-row transmit (Tx) or transceiver (TxRx) arrays is the decoupling of the array's loop elements. Overlapping of the surface loops allows the decoupling of adjacent elements and also helps to improve the radiofrequency field profile by increasing the penetration depth and eliminating voids between the loops. This also simplifies the design by reducing the number of decoupling circuits. At the same time, overlapping may compromise decoupling by generating high resistive (electric) coupling near the overlap, which cannot be compensated for by common decoupling techniques. Previously, based on analytical modeling, we demonstrated that electric coupling has strong frequency and loading dependence, and, at 9.4T, both the magnetic and electric coupling between two heavily loaded loops can be compensated at the same time simply by overlapping the loops. As a result, excellent decoupling was obtained between adjacent loops of an eight-loop single-row (1×8) human head tight-fit TxRx array. In this work, we designed and constructed a 9.4-T (400-MHz) 16-loop double-row (2×8) overlapped TxRx head array based on the results of the analytical and numerical electromagnetic modeling. We demonstrated that, simply by the optimal overlap of array loops, a very good decoupling can be obtained without additional decoupling strategies. The constructed TxRx array provides whole-brain coverage and approximately 1.5 times greater Tx efficiency relative to a transmit-only/receive-only (ToRo) array, which consists of a larger Tx-only array and a nested tight-fit 31-loop receive (Rx)-only array. At the same time, the ToRo array provides greater peripheral signal-to-noise ratio (SNR) and better Rx parallel performance in the head-feet direction. Overall, our work provides a recipe for a simple, robust and very Tx-efficient design suitable for parallel transmission and whole-brain imaging at ultra-high fields.

IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization

IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization

Guest Editorial

This Mini-Special Issue of the IEEE Transactions on Microwave Theory and Techniques includes five expanded papers from the IEEE International Conference on Numerical Electromagnetic Modeling and Optimization for RF, microwave, and terahertz applications (NEMO), held in Beijing, China, July 27–29, 2016.

Third IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization [Conference Report

Presents information on the Third IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization.

Guest Editorial Mini-Special Issue on the 2015 IEEE International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO2015) for RF, Microwave, and Terahertz Applications

Electromagnetics lay the foundation of electronic, electrical, and computer science technology. Without it, we would not have electric power, cars, radios, cellular phones, computers, and many more technologies that we take for granted; our world would be totally different and our professions in electrical and computer engineering would not exist. Human beings have long known about electromagnetism and early devices include the compass and signaling fire lights. A beautiful theory of the electromagnetic field was put forward by James Clerk Maxwell and later reformulated by Oliver Heaviside and Heinrich Hertz, all of them being among the 19th century greatest physicists and mathematicians. Today, when we deal with electromagnetic problems that embody power, radio, microwave, terahertz, and optical applications, we have to solve Maxwell’s equations, although approximate models of Maxwell’s equations, circuits and lump elements, are often used, especially at low frequencies.

High-Sensitivity Phased Array Receivers for Radio Astronomy

Phased arrays have a long history in radio astronomy. Large, sparse synthesis arrays have been in use for decades to capture high-resolution images of deep space objects. More recent work has extended the range of applications to other types of arrays, including aperture arrays (AAs) and phased array feeds (PAFs) for multibeam reflector antennas. The extreme sensitivity required for astronomical instrumentation is driving advances in numerical electromagnetic modeling, design optimization of large arrays, low noise amplifiers, minimization of receiver noise, cryogenic PAFs, array calibration, optimal beamforming, interferometric imaging, and array signal processing algorithms for radio-frequency interference mitigation. We give an overview of research progress, current and planned array-based instruments, and open challenges in these areas related to the new generation of sparse arrays, PAFs, and AAs that are in development for astronomical observatories around the world.

Purcell enhancement and focusing effects in plasmonic nanoantenna arrays

This paper presents measured fluorescence results for PMMA dye-coated 5×5 gold plasmonic nanoantenna arrays. We use numerical electromagnetic modeling to show how array size and element spacing can be used to control emitted beam shape and compare this with experimental data. The Friis formula from RF antenna theory is used to calculate the intensity enhancement produced by the array. A figure of merit is then developed, which accounts for the very small mode volume from which the array emission is occurring.

Broadband high efficiency silicon nanowire arrays with radial diversity within diamond-like geometrical distribution for photovoltaic applications.

In this study we report novel silicon nanowire (SiNW) array structures that have near-unity absorption spectrum. The design of the new SiNW arrays is based on radial diversity of nanowires with periodic diamond-like array (DLA) structures. Different array structures are studied with a focus on two array structures: limited and broad diversity DLA structures. Numerical electromagnetic modeling is used to study the light-array interaction and to compute the optical properties of SiNW arrays. The proposed arrays show superior performance over other types of SiNW arrays. Significant enhancement of the array absorption is achieved over the entire solar spectrum of interest with significant reduction of the amount of material. The arrays show performance independent of angle of incidence up to 70 degrees, and polarization. The proposed arrays achieved ultimate efficiency as high as 39% with filling fraction as low as 19%.

Comparison of Theoretical and Numerical Electromagnetic Modeling for HTS Synchronous Generator

Comparison of Theoretical and Numerical Electromagnetic Modeling for HTS Synchronous Generator

Guest Editorial [Mini-Special Issue on 2014 IEEE International Conference on Numerical Electromagnetic Modeling and Optimization for RF, Microwave, and Terahertz Applications (NEMO2014

The nine papers in this mini-special issue are expanded versions of papers presented at the IEEE International Conference on Numerical Electromagnetic Modeling and Optimization for RF, Microwave, and Terahertz Applications (NEMO2014), held in Pavia, Italy, May 14-16, 2014.

Rigorous Network and Full-Wave Electromagnetic Modeling of Wireless Power Transfer Links

The proposed approach makes use of full-wave electromagnetic modeling of wireless power transfer links in order to derive the network characterization, e.g., in terms of scattering or impedance matrix. Once the latter is obtained, we show that network theory provides the appropriate matching impedances for achieving either maximum efficiency, maximum power on the load, or conjugate matching. The proposed approach also permits to derive closed-form matching networks and expressions for power and efficiency. An example of full-wave numerical electromagnetic modeling of a wireless power transfer link is presented. The selected example, which is similar to the experiment published by Kurs , shows the importance of selecting the appropriate source/load impedance for obtaining significative results.