Electrodynamic Model Research Articles

Electrodynamic model of an optical multiplexer

Electrodynamic model of an optical multiplexer

Microwave lens ray tracing method as a tool for optimizing the parameters of beamforming circuits of antenna arrays

In the paper, a microwave lens tracing method is studied, which takes into account the influence of the beam-forming circuit elements on the amplitude distribution of the field over the antenna array aperture and multiple reflections of rays inside the lens cavity. An approach has been used that makes it possible to simulate the structure of microwave lenses and take into account the effect of mutual bonds inside the lens body. The proposed procedures are aimed at reducing time costs in the design of lens-type beam-forming circuits in antenna arrays of radio electronic equipment in the microwave-EHF wavelength ranges. The results of comparison of the ray tracing method and electrodynamic modeling of microwave lenses have been presented.

TEM-камера открытого исполнения для испытаний малогабаритных радиоэлектронных средств на электромагнитную совместимость

This paper presents the design and fabrication of an open TEM cell. It allows you to measure the radiated emission and immunity of radioelectronic devices. The size of the EUT should not exceed 184×162×30 mm. Performed analytical and quasi-static analysis of the regular part of the TEM cell. In the frequency range up to 1.4 GHz the reflection coefficient |S11| of the regular part does not exceed minus 45 dB. The electrodynamic model of the TEM cell is developed and the geometric parameters are optimized using a genetic algorithm. Analysis of the electrodynamic model showed that in the frequency range up to 920 MHz the voltage standing wave ratio (VSWR) does not exceed 1.3. The inequality of the electric field in the area of EUT placement is not more than 6 dB in the frequency range up to 875 MHz. The validity of the obtained results is checked using the numerical methods of finite elements and the transmission line matrix. A solid-state model of the TEM cell is developed to evaluate the effect of the design features of the assembly. The frequency dependences of |S11| of the solid‑state model do not exceed minus 17.69 dB in the frequency range up to 916 MHz. The TEM cell is fabricated by laser cutting and bending aluminum sheet metal. Using a vector circuit analyzer Micran R4M-18 measured S‑parameters of the fabricated TEM cell. The transmission coefficient |S21| of the fabricated TEM cell in the frequency range up to 936 MHz does not exceed minus 2.2 dB. The reflection coefficient |S11| does not exceed minus 17.69 dB. The results of radiated emission measurements of the Altera Cyclone IV FPGA debug board in the frequency range up to 1 GHz with a fabricated TEM cell is presented.

Ensuring the performance of modified microstrip loops in the frequency band

Problem statement. Microstrip loop structures of various configurations are widely used to form topologies of multi-pole microwave devices. In this regard, there is a need to study the frequency properties and topological features of the construction of loop structures that determine the amplitude and phase frequency characteristics, as well as the overall parameters of a microstrip radio engineering device. Objective. Studying of frequency characteristics of T- and U-shaped loop configurations implemented on the basis of high-resistance and low-resistance segments of microstrip transmission lines that allow configuring small-sized topologies of multi-pole devices with acceptable electrical characteristics. Results. A number of basic topologies of loop structures designed to function in given frequency bands have been studied. With the help of electrodynamic modeling and parametric optimization, according to a number of criteria (given wave resistance, phase shift, reflection coefficient), the necessary geometric dimensions of the modified topologies were determined. The dependence of the frequency band on the geometric dimensions of the low-resistance loop of the T-section is revealed. By the level of “minus” 20 dB from the maximum of the reflection coefficient, the values of the frequency band width of two types of T-structures – symmetrical and counter-pin - were determined and compared. It is shown that the U-shaped section is characterized by an increased frequency band due to better matching, however, its geometric dimensions exceed the dimensions of the basic T-structures. Practical significance. Modified microstrip loop structures in some cases are able to effectively replace quarter-wave segments of transmission lines, on the basis of which most microwave devices are formed (directional couplers, power dividers, electric filters, phase shifters, crossovers, etc.). The use of combinations of T- and U-shaped structures leads to a significant reduction in the area of microstrip devices designed to operate in the UHF and Microwave bands.

Next generation electrodynamic model for geospace

Next generation electrodynamic model for geospace

Chemical Activity of Low Altitude (50 km) Sprite Streamers

AbstractA three‐stage simulation is used to explore the chemical influence of low altitude (50 km) sprite streamers on the atmosphere, including the chemical trail after the streamer has faded away. In the first stage (streamer phase) a 2D electrodynamical streamer model quantifies the generation of NOx and N2O, and the removal of ozone (O3) by a downward propagating streamer during Δtstreamer = 80 μs. This streamer propagation leads to a distinctive region in the streamer channel, the glow, where the electric field is enhanced. In the second stage (glow phase), the computed densities of the first stage are used as initial conditions for a 0D model to study the chemical evolution of the streamer channel, where we assume a remanent field of 100 Td for the glow and 0 Td elsewhere. This stage lasts Δtglow = 85 μs, the typical glow lifetime at 50 km. Finally, in the third stage (post‐streamer phase), we use the same 0D model, switch off the field in the glow region and let the whole streamer wake evolve roughly 100 s (100 s − Δtglow). Results show a key species such as O3 is mainly depleted during the streamer phase while NOx and N2O are predominantly produced during the same phase. We also compute the local increase of NO2 by sprite streamers at ∼50 km and find out that it could account for the measurable NO2 anomaly over thunderstorms reported from satellite‐based measurements.

Edge effects on the electromagnetic response of inhomogeneous type-II superconductors

From a macroscopic point of view, the edges of a type II superconductor are degraded non-homogeneous regions compared with the bulk of the sample. This paper presents numerical simulations of a long superconducting bar with square cross section subjected to an axial external magnetic field, the edges effect on its electromagnetic properties is studied. The edges of the sample are modeled as finite width regions with lower critical current density than the rest of the material. The simulations are based on a continuum electrodynamics model which describes the magnetic induction dynamics of partially penetrated states. Unlike a simpler homogeneous superconductor, in an inhomogeneous material rough flux fronts are formed. It was established that the stochastic profile of the current density produces jets of magnetic flux near a macrodefect.

Artificial Magnetic Conductors Based on Frequency Selective Surfaces

New band-passing frequency-selective surfaces (FSSs) are proposed and investigated. Formulas for calculating the modulus and phase of the reflection coefficient of artificial magnetic conductors are obtained based on the proposed FSSs. The comparison of the results of electrodynamic modeling and calculation by formulas is carried out. The possibility of expanding the operating frequency band is shown.

Model of relativistic superconductivity

We propose a simplified 2D effective scalar electrodynamics model of relativistic type-II superconductivity. Within this framework, we discuss possible electromagnetic (EM) behaviors of superconductivity along the lines of the nonrelativistic Ginzburg–Landau (GL) theory. This model may be of significance to study very diverse physical phenomena such as a nonlinear version of the electron–hole conversion by a superconductor and electron-positron dynamics around neutron stars. We briefly comment on extending the model to study the 3D dynamics of vortex–vortex interactions and Abrikosov fluxonics.

Electrodynamic Model of a Combustion Chamber with an Initiator of a Subcritical Streamer Discharge Positioned Parallel to the Optical Axis of the Chamber

Electrodynamic Model of a Combustion Chamber with an Initiator of a Subcritical Streamer Discharge Positioned Parallel to the Optical Axis of the Chamber

Effective quantum electrodynamics: One-dimensional model of the relativistic hydrogen-like atom.

We consider a one-dimensional effective quantum electrodynamics (QED) model of the relativistic hydrogen-like atom using delta-potential interactions. We discuss the general exact theory and the Hartree-Fock approximation. The present one-dimensional effective QED model shares the essential physical feature of the three-dimensional theory: the nuclear charge polarizes the vacuum state (creation of electron-positron pairs), which results in a QED Lamb-type shift of the bound-state energy. Yet, this 1D effective QED model eliminates some of the most serious technical difficulties of the three-dimensional theory coming from renormalization. We show how to calculate the vacuum-polarization density at zeroth order in the two-particle interaction and the QED Lamb-type shift of the bound-state energy at first order in the two-particle interaction. The present work may be considered a step toward the development of a quantum-chemistry effective QED theory of atoms and molecules.

Accurate measurements of the ferromagnetic resonance linewidth of single crystal BaM hexaferrite spheres employing magnetic plasmon resonance theory

Accurate measurements of the intrinsic ferromagnetic linewidth of a single-crystal Sc-doped hexagonal M-type barium ferrite (BaM) 308-µm-diameter sphere at millimeter-wave frequencies employing a subwavelength cavity are described. The magnetic hysteresis of the resonance frequency and Q-factor of the dominant resonance (which has a plasmonic character) in a hexaferrite sphere are reported. Measurements performed in a fixture open to free space also show that the ferromagnetic linewidth significantly increases as compared to measurements in a closed cavity. This effect can be attributed to radiation losses, as revealed by an electrodynamic magnetic plasmon resonance model, and is relevant for measurements in open structures, such as microstrip lines or coplanar waveguides. The impact of finite resistivity on the linewidth was also analyzed.

ОСОБЕННОСТИ ПОСТРОЕНИЯ МОДЕЛИ ЗЕРКАЛЬНОЙ АНТЕННЫ С УЧЕТОМ ВЛИЯНИЯ МЕТЕОРОЛОГИЧЕСКИХ ФАКТОРОВ

An electrodynamic model of a millimeter-range single-mirror antenna with a puddle in the reflector is given. As a justification for the need for a model, the influence of rainfall on the design of millimeter-range mirror antennas was assessed. The aim of the study was to create a model of the parabolic reflector of a mirror antenna with an aqueous precipitation layer, with parameters chosen for the climatic region in which the antenna is located. An analysis of known models of single mirror antennas with a layer of precipitation has been carried out. It has been shown that the known models do not describe the operation of a millimeter-range mirror antenna with a reflector in which a puddle of water has formed. It is suggested that the influence of this layer on the directional characteristics of the antenna be assessed with the aperture method used for mirror antennas with reflector profile defects. The results of the modelling of the directivity pattern of a mirror antenna with a puddle of water in the reflector are presented. It is shown that the appearance of a puddle leads to an asymmetric change in the height of the first side lobes of the directivity pattern in the vertical plane. In the horizontal plane, changes are observed in the growth level of each side lobe, except for the first one. The lobes' symmetry is not affected. Research focus: The process of emitting a millimeter electromagnetic wave using a single mirror antenna with a layer of water in the reflector. Subject of the study: "Mirror antenna reflector with water precipitation layer - millimeter wavelength electromagnetic wave" system. Methods: Electromagnetic meteorological method, modified aperture method, modified Ruze method, statistical meteorological method. Main result: A wireless communication system using the magnetic component of the electromagnetic field has been developed. Practical relevance: The results of this research may be useful in the design of millimeter-range mirror antennas to assess the influence of meteorological precipitation on the directivity characteristics. The work was presented at the VIII All-Russian Microwave Conference "Microwave week 2022" in Moscow.

Experimental study of radiating structures with substrates of planar chiral metamaterial based on S-elements and gammadion

At the moment, the actual scientific and technical task is to reduce the weight and size characteristics of the metamaterial, as well as to reduce the technological complexity of manufacturing chiral elements. This article is devoted to experimental studies of radiating structures with substrates of planar chiral metamaterial based on S-elements and gammadions, which make it possible to determine their real characteristics, as well as to verify the results obtained by electrodynamic modeling methods. The obtained results of an experimental study of the characteristics of layouts of planar chiral metamaterials based on S-elements and gammadions indicate the presence of "screen" properties in a number of frequency ranges. At the same time, the "chiral properties" of these planar metamaterials are expressed worse than those of bulk metamaterials based on spirals. These chiral metamaterials can be used in solving problems of electromagnetic compatibility of closely located radio-electronic means.

Quark-antiquark confinement and nonlinear electrodynamics

Cornell potential is known to represent the quark-antiquark confinement interaction. In addition to the Cornell potential, there have been other interactions in the literature that demonstrate confining structure in the quark-antiquark system. Guendelman has proposed a nonlinear electrodynamics (NED) model which results in electric potential in the form of Cornell interaction. In this study, we propose two NED models whose electric potential is in the form of two other confining potentials. We also study the coupling of gravity to one of these models which are in the form of a correction to linear Maxwell's theory. We find spacetime which can be a black hole or a naked singular particle. In the zeroth approximation, we examine the circular speed of a distant test particle orbiting the central black hole. The Newtonian potential due to the spacetime at the location of the distant particle possesses an additional term proportional to the NED parameter. Due to the presence of such a term, the speed-radius curve gets improved from the pure Reissner-Nordstrom. It is a kind of weaker confinement acting on distant parts of a galaxy due to a supermassive central black hole.

Flux-based three-dimensional electrodynamic modeling approach to superconducting circuits and materials

Modeling the behavior of superconducting electronic circuits containing Josephson junctions is crucial for the design of superconducting information processors and devices. In this paper, we introduce DEC-QED, a computational approach for modeling the electrodynamics of superconducting electronic circuits containing Josephson junctions in arbitrary three-dimensional electromagnetic environments. DEC-QED captures the nonlinear response and induced currents in BCS superconductors and accurately captures phenomena such as the Meissner effect, flux quantization, and Josephson effects. Using a spatial coarse-graining formulation based on discrete exterior calculus (DEC), DEC-QED can accurately simulate transient and long-time dynamics in superconductors. The expression of the entire electrodynamic problem in terms of the gauge-invariant flux field and charges makes the resulting classical field theory suitable for second quantization.

Multiscale modeling and simulation of surface‐enhanced spectroscopy and plasmonic photocatalysis

AbstractPlasmonic metal nanoparticles (PMNPs) are capable of localized surface plasmon resonance (LSPR) and have become an important component in many experimental settings, such as the surface‐enhanced spectroscopy and plasmonic photocatalysts, in which PMNPs are used to regulate the nearby molecular photophysical and photochemical behaviors by means of the complex interplay between the plasmon and molecular quantum transitions. Building computational models of these coupled plasmon‐molecule systems can help us better understand the bound molecular properties and reactivity, and make better decisions to design and control such systems. Ab initio modeling the nanosystem remains highly challenging. Many hybrid quantum‐classical (or ‐quantum) computing models have thus been developed to model the coupled systems, in which the molecular system of interest is designated as the quantum mechanical (QM) sub‐region and treated by the excited‐state electronic structure approaches such as the time‐dependent density functional theory (TDDFT), while the electromagnetic response of PMNPs is usually described using either a computational/classical electrodynamic (CED) model, polarizable continuum model(PCM), a polarizable molecular mechanics (MM) force field, or a collective of optical oscillators in QED model, leading to many hybrid approaches, such as QM/CED, QM/PCM, QM/MM or ab initio QED. In this review, we summarize recent advances in the development of these hybrid models as well as their advantages and limitations, with a specific emphasis on the TDDFT‐based approaches. Some numerical simulations on the plasmon‐enhanced absorption and Raman spectroscopy, plasmon‐driven water splitting reaction and interfacial electronic injection dynamics in dye‐sensitized solar cell are demonstrated.This article is categorized under: Electronic Structure Theory > Ab Initio Electronic Structure Methods Theoretical and Physical Chemistry > Spectroscopy Software > Quantum Chemistry Electronic Structure Theory > Combined QM/MM Methods

Validation of Ionospheric Specifications During Geomagnetic Storms: TEC and foF2 During the 2013 March Storm Event‐II

AbstractAssessing space weather modeling capability is a key element in improving existing models and developing new ones. In order to track improvement of the models and investigate impacts of forcing, from the lower atmosphere below and from the magnetosphere above, on the performance of ionosphere‐thermosphere models, we expand our previous assessment for 2013 March storm event (Shim et al., 2018, https://doi.org/10.1029/2018SW002034). In this study, we evaluate new simulations from upgraded models (the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) model version 4.1 and the Global Ionosphere Thermosphere Model (GITM) version 21.11) and from the NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM‐X) version 2.2 including eight simulations in the previous study. A simulation from the NCAR Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model version 2 (TIE‐GCM 2.0) is also included for comparison with WACCM‐X. TEC and foF2 changes from quiet‐time background are considered to evaluate the model performance on the storm impacts. For evaluation, we employ four skill scores: Correlation coefficient (CC), root‐mean square error (RMSE), ratio of the modeled to observed maximum percentage changes (Yield), and timing error (TE). It is found that the models tend to underestimate the storm‐time enhancements of foF2 (F2‐layer critical frequency) and TEC (Total Electron Content) and to predict foF2 and/or TEC better in North America but worse in the Southern Hemisphere. The ensemble simulation for TEC is comparable to results from a data assimilation model (Utah State University‐Global Assimilation of Ionospheric Measurements (USU‐GAIM)) with differences in skill score less than 3% and 6% for CC and RMSE, respectively.

Electrodynamic and Probabilistic Models of Electrically Controlled THz Filters Based on Graphene–Dielectric Metamaterials

Electrodynamic and Probabilistic Models of Electrically Controlled THz Filters Based on Graphene–Dielectric Metamaterials

Dyonic matter equations, exact point-source solutions, and charged black holes in generalized Born-Infeld theory

We derive the equations of motion governing static dyonic matters, described in terms of two real scalar fields, in nonlinear electrodynamics of the Born--Infeld theory type. We then obtain exact finite-energy solutions of these equations in the quadratic and logarithmic nonlinearity cases subject to dyonic point-charge sources and construct dyonically charged black holes with relegated curvature singularities. In the case of quadratic nonlinearity, which is the core model of this work, we show that dyonic solutions enable us to restore electromagnetic symmetry, which is known to be broken in non-dyonic situations by exclusion of monopoles. We further demonstrate that in the context of k-essence cosmology the nonlinear electrodynamics models possess their own distinctive signatures in light of the underlying equations of state of the cosmic fluids they represent. In this context, the quadratic and logarithmic models are shown to resolve a density-pressure inconsistency issue exhibited by the original Born--Infeld model k-essence action function as well as by all of its fractional-powered extensions. Moreover, it is shown that the quadratic model is uniquely positioned to give rise to a radiation-dominated era in the early universe among all the polynomial models and other examples considered.