Broadband Electromagnetic Field Research Articles

The exposure analysis of the long-term broadband EMF monitoring in the campus area of the University of Novi Sad.

Due to wide prevalence of electromagnetic field (EMF) sources in human surrounding, EMF-level measurements and corresponding exposure assessment have imposed as an important topic. With an intention to present an approach to the long-term exposure assessment in EMF RATEL network, this paper conveys a high-level statistical analysis of the high-frequency exposure data, acquired during the 5-y time period, for the case study of monitoring sensor installed in the area of the Novi Sad University campus. Time series of exposure values were averaged on a daily, weekly, and monthly basis, and their yearly comparison was performed. Results showed clear differences between the day and night hours, as well between working and weekend days. Regarding exposure values, averaged on the monthly basis, the impact of COVID-19 pandemic in 2020 and 2021 can be noticed. Finally, the highest obtained exposure values (electric field squared) were 22 times below the maximal allowable level, according to the Serbian legislation.

Properties and technical applications of antenna arrays focused on a broadband signal

Background. Currently, antenna arrays focused in the near-radiated field zone are being actively studied. The basic properties and characteristics of focused antenna systems using narrowband signals are known. It is possible to expand the technical capabilities of devices using focused electromagnetic fields through the use of broadband signals. This article is devoted to a description of the properties and a number of technical applications of antenna arrays focused in the near-radiated field zone using a broadband signal.
 Aim. The main aim of this article is to describe the basic properties of focused broadband electromagnetic fields and develop practical application options based on them.
 Methods. Achieving the goal of the article is due to the use of well-known principles of electrodynamics and aperture theory of antennas.
 Results. The features of the formation of focused broadband electromagnetic fields are shown and their main properties are given. Options for the technical application of focused broadband antennas in radio communication and direction finding tasks are proposed.
 Conclusion. The results obtained confirm the importance of assessing the properties of broadband focused antennas and developing a number of technical proposals based on them

Fluid-Kinetic Variations in the Storm-Time Inner Magnetosphere.

Storm‐time broadband electromagnetic field variations along the interface between the dipolar field of the Earth's inner‐magnetosphere and the stretched fields of the plasma‐sheet are decomposed as a superposition of fluid‐kinetic modes. Using model eigen‐vectors operating on the full set of Van Allen Probes fields measurements it is shown how these variations are composed of a broad spectrum of dispersive Alfvén waves with significant spectral energy densities in the fast and slow modes over scales extending into the kinetic range. These modes occupy volumes in k‐space that define the field variations observed at each spacecraft frame frequency (fsc). They are in aggregate not necessarily planar and often comprise filamentary structures with no distinct propagation direction in the perpendicular plane. Within these volumes the characteristic parallel phase speeds of the fast and Alfvénic modes coincide over a broad range of fsc suggestive of coupling/conversion between modes.

Infrared rainbow trapping via optical Tamm modes in an one-dimensional dielectric chirped photonic crystals.

The phenomenon of trapping a broad spectrum of light is known as "rainbow trapping" and is achieved by using all-dielectric, hybrid metallo-dielectric, or all-metallic configurations. The latter architectures allow strong confinement but exhibit very high ohmic losses. This results in practical lifetimes of trapped modes to less than 1 ps. Therefore, novel strategies are required to be devised for trapping and, subsequently, releasing broadband electromagnetic field with lifetime >1ps. We present a rainbow trapping configuration using the excitation of multiple optical Tamm (OT) modes in an one-dimensional chirped photonic crystal (CPC) designed for adiabatically coupling counterpropagating modes. In the geometry, the backscattered phase undergoes multiple discontinuities (=π), which enables excitation of many OT modes in the presence of a thin plasmon-active metal, which is placed adjacent to the terminating layer of CPC. All the OT modes are spatially separated in the CPC, and the strong modal confinement manifests into group velocities as low as 0.17c. The time-domain simulations depict mode-localization in the dielectric sections of CPC, which manifest into lifetimes ∼3ps.

Wideband Electromagnetic Field Vector Antenna Array Technique and Direction Finding Algorithm

Wideband (UWB) technology has been widely used in ultra-wideband wireless communication, radar detection and other fields because of its advantages such as wide working frequency band, fast transmission rate and accurate positioning. This paper mainly studies the broadband electromagnetic field vector antenna array technology and direction finding algorithm. In this paper, the structure of a broadband resonant antenna unit is designed. The antenna unit adopts the form of printed antenna, which has both the advantages of planar antenna structure and wider bandwidth. For array antenna amplitude-phase error exists when the ideal direction, of the environment theory analyzes the mutual coupling and antenna array yuan border effect influence on beam shaper MUSIC algorithm, this paper proposes a anti-interference antenna phase characteristic difference of the calibration method of using 3 d electromagnetic simulation software HFSS, the mutual coupling matrix calculation, the amplitude-phase error correction, and has carried on the MATLAB simulation, the simulation results show that the method of direction finding pitching Angle error of less than 1, the direction finding azimuth error is less than 2, can be used for the beidou anti-interference antenna of direction finding.

Quantitative terahertz emission nanoscopy with multiresonant near-field probes.

By sampling terahertz waveforms emitted from InAs surfaces, we reveal how the entire, realistic geometry of typical near-field probes drastically impacts the broadband electromagnetic fields. In the time domain, these modifications manifest as a shift in the carrier-envelope phase and emergence of a replica pulse with a time delay dictated by the length of the cantilever. This interpretation is fully corroborated by quantitative simulations of terahertz emission nanoscopy based on the finite element method. Our approach provides a solid theoretical framework for quantitative nanospectroscopy and sets the stage for a reliable description of subcycle, near-field microscopy at terahertz frequencies.

ИЗМЕНЕНИЯ ИММУНОЛОГИЧЕСКОГО ОТВЕТА В РЕАКЦИИ НСТ С ПЕРИТОНЕАЛЬНЫМИ МАКРОФАГАМИ ПОД ДЕЙСТВИЕМ ШИРОКОПОЛОСНОГО ЭЛЕКТРОМАГНИТНОГО ИЗЛУЧЕНИЯ В ЭКСПЕРИМЕНТЕ

Summary The article presents the results of research on the study of the effect of broadband electromagnetic fields on a macroorganism in an experiment. Electromagnetic fields with different characteristics can affect the systems of living organisms in different ways, including the immune system, which is sensitive to electromagnetic influences. Broadband electromagnetic fields have an immunostimulating effect, as evidenced by the increase in the enzymatic activity of peritoneal macrophages in reaction with nitro blue tetrazolium.

A Compact, Broadband, and Calculable Electromagnetic Field Source for Quality Assurance in EMC Testing

The aim of this article is to describe the design, realization, and characterization of a compact, broadband, and calculable electromagnetic field source. The source has been extensively used as a traveling reference radiator in proficiency tests of radiated emission measurements. The result of its characterization has been validated by more than 500 measurements over the frequency range from 50 to 6000 MHz in semianechoic (3 and 10 m) and fully anechoic (3 m) chambers. The use of the source as a reference radiator for emission measurements could be extended to other testing facilities, such as transverse electromagnetic waveguides and reverberation chambers.

Research on wide-band electromagnetic scattering characteristics of random distributed objects using Monte Carlo method

In the engineering applications, the distribution of objects is mostly random. Therefore, scattering analysis of randomly distributed objects has been one of the important problems in broadband electromagnetic calculation field. To resolve the problem, the Asymptotic Waveform Evaluation technique in conjunction with Monte Carlo Method is presented. First, the stochastic distribution is modeled by the Monte Carlo Method, and then the Asymptotic Waveform Evaluation technique using Padé approximation is utilized to achieve the Radar Cross Section at a wide frequency band. Numerical results show that the Asymptotic Waveform Evaluation technique can solve the random distributed object problems efficiently and accurately.

ИЗМЕНЕНИЯ ИММУНОЛОГИЧЕСКОГО ОТВЕТА В РЕАКЦИИ НСТ С ПЕРИТОНЕАЛЬНЫМИ МАКРОФАГАМИ ПОД ДЕЙСТВИЕМ ШИРОКОПОЛОСНОГО ЭЛЕКТРОМАГНИТНОГО ИЗЛУЧЕНИЯ В ЭКСПЕРИМЕНТЕ

The article presents the results of research on the study of the effect of broadband electromagnetic fields on a macroorganism in an experiment. Electromagnetic fields with different characteristics can affect the systems of living organisms in different ways, including the immune system, which is sensitive to electromagnetic influences. Broadband electromagnetic fields have an immunostimulating effect, as evidenced by the increase in the enzymatic activity of peritoneal macrophages in reaction with nitro blue tetrazolium.

Mixed Finite Element Method for Full-Wave Simulation of Bioelectromagnetism From DC to Microwave Frequencies.

Bioelectromagnetism focuses on the study of electromagnetic fields in biological tissues from direct current (DC) to optical frequencies. It is challenging to develop an electromagnetics (EM) simulation method to cover this entire frequency band due to the electrically small/large scattering problem at extremely low/high frequencies. This paper focuses on the band from DC to microwave frequencies in bioelectromagnetism. Its main research objective is to develop a method that can overcome the low frequency breakdown problem at low frequencies (practically DC) and still stay stable at microwave frequencies. Based on the scattered field vector Helmholtz equation, the mixed finite element method (mixed FEM) is developed for the broadband electromagnetic field simulation in biological tissues. By imposing Gauss' law as the constraint condition, the mixed FEM overcomes the low frequency breakdown problem without resorting to the quasi-static approximation and remains effective and accurate at high frequencies. Extremely low frequency and high frequency numerical results are demonstrated to verify that the mixed FEM is a stable full-wave electromagnetic field simulation method for the full-bandwidth bioelectromagnetism.

Non-Wiener Dynamics of Open Systems for Nonzero Number Density of Surrounding Photons

We propose a collective decay model for a localized ensemble of identical atoms in a vacuum broadband electromagnetic field with a nonzero photon number density considering second-order terms in the atom–field interaction constant. The model is based on the stochastic differential equation for the evolution operator for the atomic ensemble and surroundings, which is controlled by the main quantum random processes and independent classical Wiener processes. It is shown that in some cases, nonzero photon number density does not influence the suppression of collective emission of atoms, and its existence is manifested as an additional mechanism of redistribution of atoms over collective sublevels.

Notice of Retraction: A Compact, Broadband, Calculable Electromagnetic Field Source for Quality Assurance in EMC Testing

The aim of this article is to describe the design, realization, and characterization of a compact, broadband, and calculable electromagnetic field source. The source has been extensively used as a traveling reference radiator in proficiency tests of radiated emission measurements. The result of its characterization has been validated by more than 500 measurements over the frequency range from 50 to 6000 MHz in semianechoic (3 and 10 m) and fully anechoic (3 m) chambers. The use of the source as a reference radiator for emission measurements could be extended to other testing facilities, such as transverse electromagnetic waveguides and reverberation chambers.

Models of the Dynamics of Spatially Separated Broadband Electromagnetic Fields Interacting with Resonant Atoms

The Markov model of spontaneous emission of an atom localized in a spatial region with a broadband electromagnetic field with zero photon density is considered in the conditions of coupling of the electromagnetic field with the broadband field of a neighboring space. The evolution operator of the system and the kinetic equation for the atom are obtained. It is shown that the field coupling constant affects the rate of spontaneous emission of the atom, but is not manifested in the atomic frequency shift. The analytic expression for the radiative decay constant for the atom is found to be analogous in a certain sense to the expression for the decay constant for a singly excited localized ensemble of identical atoms in the conditions when the effect of stabilization of its excited state by the Stark interaction with the vacuum broadband electromagnetic field is manifested. The model is formulated based on quantum stochastic differential equations of the non- Wiener type and the generalized algebra of the Ito differential of quantum random processes.

Međulaboratorijska ispitivanja kod širokopojasnih merenja elektromagnetskih polja

Međulaboratorijska ispitivanja kod širokopojasnih merenja elektromagnetskih polja

The adaptive boundary approach for exposure assessment in a broadband EMF monitoring

Abstract The boundary approach for the assessment of daily exposure to electromagnetic fields (EMF) has been recently proposed for the continuous and broadband EMF monitoring of the Serbian Electromagnetic Field Monitoring Network – SEMONT. This approach is based on the determination of the daily upper and lower exposure boundaries, combining data of the continuous in situ EMF monitoring in a broadband frequency range and the minimal and maximal prescribed reference levels. The real exposure is positioned between these boundaries. In this paper, the enhancement of the boundary approach is presented. By adjusting the existing boundaries and reducing the difference between them, the precision of the daily exposure assessment in the SEMONT system has been improved. The frequency selective measurement has been used to determine the frequencies on which EMF sources radiate over a particular area and in situ location. Consequently, the new minimal and maximal reference levels can be selected; these are suitable for a particular in situ location and should be used for the calculation of exposure boundaries on that location. A simple in situ test measurement of the high-frequency electric field strength was performed, in order to verify the proposed adaptive boundary approach. The analysis shows that this approach attained reduction in boundaries difference of 36.25%, regarding the Serbian legislation, resulting with the increased precision of the daily exposure assessment for the broadband EMF monitoring.

Weak Broadband Electromagnetic Fields are More Disruptive to Magnetic Compass Orientation in a Night-Migratory Songbird (Erithacus rubecula) than Strong Narrow-Band Fields.

Magnetic compass orientation in night-migratory songbirds is embedded in the visual system and seems to be based on a light-dependent radical pair mechanism. Recent findings suggest that both broadband electromagnetic fields ranging from ~2 kHz to ~9 MHz and narrow-band fields at the so-called Larmor frequency for a free electron in the Earth’s magnetic field can disrupt this mechanism. However, due to local magnetic fields generated by nuclear spins, effects specific to the Larmor frequency are difficult to understand considering that the primary sensory molecule should be organic and probably a protein. We therefore constructed a purpose-built laboratory and tested the orientation capabilities of European robins in an electromagnetically silent environment, under the specific influence of four different oscillating narrow-band electromagnetic fields, at the Larmor frequency, double the Larmor frequency, 1.315 MHz or 50 Hz, and in the presence of broadband electromagnetic noise covering the range from ~2 kHz to ~9 MHz. Our results indicated that the magnetic compass orientation of European robins could not be disrupted by any of the relatively strong narrow-band electromagnetic fields employed here, but that the weak broadband field very efficiently disrupted their orientation.

Optymalizacja metodyki pomiaru wieloczęstotliwościowego pola elektromagnetycznego stacji bazowych telefonii komórkowej

This paper presents the characteristics of the mobile phone base station (BS) as an electromagnetic field (EMF) source. The most common system configurations with their construction are described. The parameters of radiated EMF in the context of the access to methods and other parameters of the radio transmission are discussed. Attention was also paid to antennas that are used in this technology. The influence of individual components of a multi-frequency EMF, most commonly found in the BS surroundings, on the resultant EMF strength value indicated by popular broadband EMF meters was analyzed. The examples of metrological characteristics of the most common EMF probes and 2 measurement scenarios of the multisystem base station, with and without microwave relays, are shown. The presented method for measuring the multi-frequency EMF using 2 broadband probes allows for the significant minimization of measurement uncertainty. Equations and formulas that can be used to calculate the actual EMF intensity from multi-frequency sources are shown. They have been verified in the laboratory conditions on a specific standard setup as well as in real conditions in a survey of the existing base station with microwave relays. Presented measurement methodology of multi-frequency EMF from BS with microwave relays, validated both in laboratory and real conditions. It has been proven that the described measurement methodology is the optimal approach to the evaluation of EMF exposure in BS surrounding. Alternative approaches with much greater uncertainty (precaution method) or more complex measuring procedure (sources exclusion method) are also presented).

Broadband low‐frequency electromagnetic waves in the inner magnetosphere

AbstractA prominent yet largely unrecognized feature of the inner magnetosphere associated with particle injections, and more generally geomagnetic storms, is the occurrence of broadband electromagnetic field fluctuations over spacecraft frame frequencies (fsc) extending from effectively zero to fsc ≳ 100 Hz. Using observations from the Van Allen Probes we show that these waves most commonly occur premidnight but are observed over a range of local times extending into the dayside magnetosphere. We find that the variation of magnetic spectral energy density with fsc obeys over several decades with a spectral breakpoint at fb ≈ 1 Hz. The values for α are lognormally distributed with α = 1.9 ± 0.6 for fsc < fb and α = 2.9 ± 0.6 for fsc > fb. A is a function of geomagnetic activity with the largest values observed over intervals of decreasing Dst index during the main phase of geomagnetic storms. At these times these waves are nearly always present in the nightside inner magnetosphere and are commonly observed from L = 3 outward. The observed variation of the electric to magnetic field amplitude with fsc is well described by a dispersive Alfvén wave model under the assumption that fsc is primarily a consequence of the Doppler shift of plasma frame structures moving over the spacecraft. The robust anticorrelation between the time rate change of the Dst index and wave spectral energy density coupled with the ability of dispersive Alfvén waves to drive transverse ion acceleration suggests that these waves may boost ion energy density in the inner magnetosphere and intensify the ring current during storm times.

Quantum dynamics of a two-level emitter with a modulated transition frequency

The resonant quantum dynamics of an excited two-level emitter is investigated via classical modulation of its transition frequency while simultaneously the radiator interacts with a broadband electromagnetic field reservoir. The frequency of modulation is selected to be of the order of the bare-state spontaneous decay rate. In this way, one can induce quantum interference effects and, consequently, quantum coherences among multiple decaying transition pathways. Depending on the modulation depth and its absolute phase, both the spontaneous emission and the frequency shift may be conveniently modified and controlled.