Field Strength Levels Research Articles

Validation study of the magnetically self‐consistent inner magnetosphere model RAM‐SCB

The validation of the magnetically self‐consistent inner magnetospheric model RAM‐SCB developed at Los Alamos National Laboratory is presented here. The model consists of two codes: a kinetic ring current–atmosphere interaction model (RAM) and a 3‐D equilibrium magnetic field code (SCB). The validation is conducted by simulating two magnetic storm events and then comparing the model results against a variety of satellite in situ observations, including the magnetic field from Cluster and Polar spacecraft, ion differential flux from the Cluster/CODIF (Composition and Distribution Function) analyzer, and the ground‐based SYM‐H index. The model prediction of the magnetic field is in good agreement with observations, which indicates the model's capability of representing well the inner magnetospheric field configuration. This provides confidence for the RAM‐SCB model to be utilized for field line and drift shell tracing, which are needed in radiation belt studies. While the SYM‐H index, which reflects the total ring current energy content, is generally reasonably reproduced by the model using the Weimer electric field model, the modeled ion differential flux clearly depends on the electric field strength, local time, and magnetic activity level. A self‐consistent electric field approach may be needed to improve the model performance in this regard.

Global Optimization of Indoor Radio Coverage

The new focus of wireless communication is shifting from voice to multimedia services. There is a growing interest in providing and improving radio coverage for mobile phones, short range radios and WLANs inside buildings. The need of such coverage appears mainly in office buildings, shopping malls, train stations where the subscriber density is very high. The cost of cellular systems and also the one of indoor wireless systems depend highly on the number of base stations required to achieve the desired coverage for a given level of field strength. There are already numerous optimization methods published which can be applied to the optimal design of such indoor networks [2,3,4,5]. The recently published methods use any heuristic technique for finding the optimal Access Point (AP) positions. Common drawbacks of the methods are the slow convergence in a complex environment like the indoor one.

MEASUREMENT OF THE ELECTRIC FIELD STRENGTH LEVEL OF THE UHF BAND IN THE BUILDING ENVIRONMENT

The digital terrestrial television which uses the electromagnetic wave of UHF band was started in December, 2003 and it will be shifted completely by July, 2011. In this paper, the electric field strength level is measured in the reception condition that is different of the distance and height and in city. As a result of the measurement, the following have been understood.1. The electric field strength level decreases as the distance parts but the influence that buildings and landform give it is larger.2. The electric field strength level increases as the reception point rises and are almost constant.3. The distance from buildings and the direction of the electromagnetic wave influence the electric field strength level because of the diffraction of it.4. The amount of attenuation at the electric field strength level is large in the city because the building is large and it is overcrowded. The study is critical data in link budget analysis of the electromagnetic wave of the digital terrestrial television.

Accuracy and coverage of the modernized Polish Maritime differential GPS system

The DGPS navigation service augments The NAVSTAR Global Positioning System by providing localized pseudorange correction factors and ancillary information which are broadcast over selected marine reference stations. The DGPS service position and integrity information satisfy requirements in coastal navigation and hydrographic surveys. Polish Maritime DGPS system has been established in 1994 and modernized (in 2009) to meet the requirements set out in IMO resolution for a future GNSS, but also to preserve backward signal compatibility of user equipment. Having finalized installation of the new technology L1, L2 reference equipment performance tests were performed. The paper presents results of the coverage modeling and accuracy measuring campaign based on long-term signal analyses of the DGPS reference station Rozewie, which was performed for 26 days in July 2009. Final results allowed to verify the coverage area of the differential signal from reference station and calculated repeatable and absolute accuracy of the system, after the technical modernization. Obtained field strength level area and position statistics (215,000 fixes) were compared to past measurements performed in 2002 (coverage) and 2005 (accuracy), when previous system infrastructure was in operation. So far, no campaigns were performed on differential Galileo. However, as signals, signal processing and receiver techniques are comparable to those know from DGPS. Because all satellite differential GNSS systems use the same transmission standard (RTCM), maritime DGPS Radiobeacons are standardized in all radio communication aspects (frequency, binary rate, modulation), then the accuracy results of differential Galileo can be expected as a similar to DGPS. Coverage of the reference station was calculated based on unique software, which calculate the signal strength level based on transmitter parameters or field signal strength measurement campaign, done in the representative points. The software works based on Baltic sea vector map, ground electric parameters and models atmospheric noise level in the transmission band.

Analysis of the possibility for the appearance of a multipactor discharge in microwave devices of accelerators with superconducting resonators

The results of the analysis of the electric strength (with respect to the multipactor discharge) of superconducting resonators and components of power-input devices for linear electron accelerators are presented. The studies were carried out using a computer program for three-dimensional (3D) modeling of a multipactor discharge developed by the authors. Dangerous levels of the field strength for resonators and dangerous ranges of the transmitted power for traveling-wave devices are revealed.

Dielectric electro‐active polymer push actuators: performance and challenges

AbstractProgress in research and development in the field of electro‐active polymers has enabled prototype fabrication, which demonstrates the future potential and versatility offered by this technology. These prototypes can be qualified as laboratory demonstrators. A new design of dielectric elastomer linear actuators is presented here. These actuators have the unique properties of being self‐supporting and core‐free. They are capable of large push forces and are fabricated based on large‐scale industrial manufacturing processes. Actuators can be easily scaled to fit specific application needs. Actuator design and construction principles, as well as modelling are presented and discussed for push InLastor® actuators. The actuators exhibit modest strokes and high actuation forces. Current design considerations indicate that the achievable force output is reduced by about 40% due to the passive ends of the actuator. Dielectric electro‐active polymer DEAP film manufacturing challenges contribute to reducing the achievable breakdown strength to 35 V µm−1 and limit the strain to modest figures. It is shown that push InLastor actuators can be operated at field strength levels above 45 V µm−1, and exhibit larger strokes and forces in good agreement with the model. At these elevated electric field levels, risks of catastrophic breakdown increase, resulting in reduced actuator lifetime. A major milestone in the manufacturing of actuators based on the DEAP technology has been achieved by Danfoss PolyPower. Large‐scale manufacturing of robust and reliable push tubular actuators is possible. Roll‐to‐roll manufacturing processes make it possible to manufacture these powerful actuators, based on PolyPower compliant electrode design. Copyright © 2010 Society of Chemical Industry

Measurement and analysis of radiofrequency radiations from some mobile phone base stations in Ghana

A survey of the radiofrequency electromagnetic radiation at public access points in the vicinity of 50 cellular phone base stations has been carried out. The primary objective was to measure and analyse the electromagnetic field strength levels emitted by antennae installed and operated by the Ghana Telecommunications Company. On all the sites measurements were made using a hand-held spectrum analyser to determine the electric field level with the 900 and 1800 MHz frequency bands. The results indicated that power densities at public access points varied from as low as 0.01 microW m(-2) to as high as 10 microW m(-2) for the frequency of 900 MHz. At a transmission frequency of 1800 MHz, the variation of power densities is from 0.01 to 100 microW m(-2). The results were found to be in compliant with the International Commission on Non-ionizing Radiological Protection guidance level but were 20 times higher than the results generally obtained for such a practice elsewhere. There is therefore a need to re-assess the situation to ensure reduction in the present level as an increase in mobile phone usage is envisaged within the next few years.

Investigation on electromagnetically induced transparency and slowdown of group velocity in an Eu3+:Y2SiO5 crystal

Electromagnetically induced transparency (EIT) and slowdown of group velocity (SGV) in Eu3+:Y2SiO5 were investigated by using density matrix equations of the interaction between light and matter and their numerical solutions. The relationship of the probe transmission with different probe detuning and coupling Rabi frequency was obtained. The influence of inhomogeneous line width on electromagnetically induced transparency and slowdown of group velocity were analyzed. Such transparency was restrained when inhomogeneous line width increased. The center transmission did not homogeneously change with an increase in ion-doped concentration. There is an optimal concentration which can make the electro-magnetically induced transparency significant. It is evident that the group velocity of the probe has a minimum value for a certain level of coupling field strength.

On Radiated Emission Limits for Pulsed Interference to Protect Modern Digital Wireless Communication Systems

Present international standards for maximum levels of unintentional radiated emission from electronic devices are developed to protect analog communication services. In this paper, we propose a set of measurement bandwidths and electric field strength levels that could be used as radiated emission limits for future radiated emission standards, based on the RMS detector, in order to protect modern digital communication services. The emission limits determined fall below the present levels for commercial electronics but above the present limits for military-specified electronics. The results in this paper give a useful picture of the order of the size of radiated electric field limits to protect modern digital communication systems/services.

DRM (Digital Radio Mondiale) Local Coverage Tests Using the 26 MHz Broadcasting Band

The digital sound broadcasting DRM (Digital Radio Mondiale) standard has established worldwide, and the number of transmissions on air has increased significantly since the approval of the standard. This paper presents the results of the one of the first DRM field trials using the 26 MHz band for local broadcasting that were carried out in Mexico. The main objective of these trials was to test the usage of the 26 MHz frequency broadcasting band to cover a local area in a similar way to FM broadcasting. This band has been usually used to broadcast long distance transmissions mainly under high sun-spot activity. When the 26 MHz band is used for local broadcasting, the tropospheric propagation is the main mechanism instead of the ionospheric refraction used in HF. At these frequencies the first Fresnel ellipsoid is usually obstructed, and multipath at urban environments is strong. In this article, practical minimum signal-to-noise ratio and field strength levels are calculated for this novel usage of the 26 MHz frequency band

Evidence for Specificity in Lipid-Rhodopsin Interactions

The interaction of bovine rhodopsin with poly- and monounsaturated lipids was studied by (1)H MAS NMR with magnetization transfer from rhodopsin to lipid. Experiments were conducted on bovine rod outer segment (ROS) disks and on recombinant membranes containing lipids with polyunsaturated, docosahexaenoyl (DHA) chains. Poly- and monounsaturated lipids interact specifically with different sites on the rhodopsin surface. Rates of magnetization transfer from protein to DHA are lipid headgroup-dependent and increased in the sequence PC < PS < PE. Boundary lipids are in fast exchange with the lipid matrix on a time scale of milliseconds or shorter. All rhodopsin photointermediates transferred magnetization preferentially to DHA-containing lipids, but highest rates were observed for Meta-III rhodopsin. The experiments show clearly that the surface of rhodopsin has sites for specific interaction with lipids. Current theories of lipid-protein interaction do not account for such surface heterogeneity.

Modern Wireless Telecommunication Technologies and Their Electromagnetic Compatibility with Life-Supporting Equipment

Hospitals rely on pagers and ordinary telephones to reach staff members in emergency situations. New telecommunication technologies such as General Packet Radio Service (GPRS), the third generation mobile phone system Universal Mobile Telecommunications System (UMTS), and Wireless Local Area Network (WLAN) might be able to replace hospital pagers if they are electromagnetically compatible with medical devices. In this study, we sought to determine if GPRS, UMTS (Wideband Code Division Multiple Access-Frequency Division Duplex [WCDMA FDD]), and WLAN (IEEE 802.11b) transmitted signals interfere with life-supporting equipment in the intensive care and operating room environment. According to United States standard, ANSI C63.18-1997, laboratory tests were performed on 76 medical devices. In addition, clinical tests during 11 operations and 100 h of intensive care were performed. UMTS and WLAN signals caused little interference. Devices using these technologies can be used safely in critical care areas and during operations, but direct contact between medical devices and wireless communication devices ought to be avoided. In the case of GPRS, at a distance of 50 cm, it caused an older infusion pump to alarm and stop infusing; the pump had to be reset. Also, 10 cases of interference with device displays occurred. GPRS can be used safely at a distance of 1 m. Terminals/cellular phones using these technologies should be allowed without restriction in public areas because the risk of interference is minimal.

Evaluation of Potential GPRS 900/1800-MHz and WCDMA 1900-MHz Interference to Consumer Electronics

This study assessed the potential for interference to consumer electronics from radio frequency (RF) fields radiated by general packet radio service (GPRS) 900/1800-MHz and wideband code division multiple access (WCDMA) 1900-MHz handsets. The study was enhanced by additional testing with fields that were characteristic of radio transmissions from GSM 900/1800-MHz handsets and 900/1800-MHz fields that comply with the requirements of the international immunity standard to RF fields, IEC 61000-4-3. Four examples of consumer electronics were tested-a television, radio, CD player, and telephone. Generally, each device exhibited some form of interference at most of the test field levels (1, 3, 10, and 30 V/m). GPRS/GSM 1800-MHz and WCDMA signals never caused interference to any device at 1 V/m. The IEC 61000-4-3-specified test signal consistently produced more audio/visual interference than GPRS- or GSM-type signals at the same test frequency and carrier field strength level. Audio/visual interference produced by WCDMA signals was generally lower than that produced by GPRS. These results, combined with the inherently lower maximum output power of WCDMA, indicate that WCDMA will usually pose a lower risk of interference compared with GPRS for similar separation distances between handsets and common items of consumer electronics.

Implantable cardiac pacemaker electromagnetic compatibility testing in a novel security system Simulator

This paper describes a novel simulator to perform electromagnetic compatibility (EMC) tests for active implantable medical devices (AIMDs) with electromagnetic fields emitted by security systems. The security system simulator was developed in response to over 100 incident reports over 17 years related to the interference of AIMD's with security systems and the lack of a standardized test method. The simulator was evaluated regarding field homogeneity, signal distortion, and maximum magnetic field strength levels. Small three-axis probes and a three-axis scanning system were designed to determine the spatial and temporal characteristics of the fields emitted by 12 different types of walk through metal detectors (WTMDs). Tests were performed on four implanted pacemakers with a saline phantom and correlated to a newly developed test method performed "in air" (without the phantom). Comparison of the simulator thresholds with tests performed in real WTMDs showed that the simulator is able to mimic the pacemaker interference. The interference thresholds found in the simulator indicate that pulsed magnetic fields are more likely to cause interference in pacemakers than sinusoidal fields. The security system simulator will help biomedical engineers, manufacturers of medical devices, and manufacturers of security systems to identify incompatible combinations of WTMDs and AIMDs early in the development stage.

On the Analysis of Statistical Distributions of UWB Signal Scattering by Random Rough Surfaces Based on Monte Carlo Simulations of Maxwell Equations

The field strength level of received signal and its statistical distributions are important in the study of signal propagation and scattering for wireless communication and remote sensing. In this paper, the scattering by random rough surface is analyzed by solving the solution of Maxwell equation. The method of moments is used to discretize the integral equation into the matrix equation. The sparse-matrix canonical grid method, which is a fast matrix solver, is applied in the analysis. Conjugate gradient (CG) method is adopted to solve the solution of matrix equation. With the solution of Maxwell equations, the magnitude of the scattered field is then used to predict the field statistics. Both time harmonic scattering and ultrawide-band (UWB) scattering are considered. For the time domain response, the electromagnetic scattered field in the vicinity of center of rough surfaces is first calculated in the frequency domain. Then the time domain signal is obtained by mean of the Fourier transform. The fading statistics are compared with that of the Rayleigh and Nakagami distributions. Results reveal that UWB signal exhibits less fading than the narrow band signal.

The Effect on Rat Thymocytes of the Simultaneous In Vivo Exposure to 50-Hz Electric and Magnetic Field and to Continuous Light

Thymus plays an important role in the immune system and can be modulated by numerous environmental factors, including electromagnetic fields (EMF). The present study has been undertaken with the aim to investigate the role of long-term exposure to extremely low frequency electric and magnetic fields (ELF-EMF) on thymocytes of rats housed in a regular dark/light cycle or under continuous light. Male Sprague-Dawley rats, 2 months old, were exposed or sham exposed for 8 months to 50-Hz sinusoidal EMF at two levels of field strength (1 kV/m, 5 μT and 5 kV/m, 100 μT, respectively). Thymus from adult animals exhibits signs of gradual atrophy mainly due to collagen deposition and fat substitution. This physiological involution may be accelerated by continuous light exposure that induces a massive death of thymocytes. The concurrent exposure to continuous light and to ELF-EMF did not change significantly the rate of mitoses compared to sham-exposed rats, whereas the amount of cell death was significantly increased, also in comparison with animals exposed to EMF in a 12-h dark-light cycle. In conclusion, long-term exposure to ELF-EMF, in animals housed under continuous light, may reinforce the alterations due to a photic stress, suggesting that, in vivo, stress and ELF-EMF exposure can act in synergy determining a more rapid involution of the thymus and might be responsible for an increased susceptibility to the potentially hazardous effects of ELF-EMF.

Quantifying Field-Induced Contrast Effects in Photoelectron Emission Microscopy

ABSTRACTSamples consisting of electrically isolated titanium lines fabricated on a titanium surface were used to quantify voltage-induced contrast effects in photoelectron emission microscopy (PEEM). Induced contrast effects were observed to extend 6 μm for a -5 V bias applied to a 303 nm tall raised line. We therefore explored, via numerical calculation, the spatial extent of the perturbation to the PEEM accelerating field caused by the bias applied across the step height. The intensity full width at half minimum agreed well with the calculated width defined by the 10% level of lateral field strength. For a line 550 nm tall, a correspondence was found for a calculated width defined by a 5% lateral field strength. It was observed that neighboring structures a few μm away affected the image contrast, for sufficiently strong applied bias. This suggests that effects can easily be induced at distances of 0.5 μm for modest applied voltages, as has been previously observed for structures buried under oxide layers 0.5 μm thick [1].

Hybrid simulations of solar wind interaction with magnetized asteroids: General characteristics

Using electromagnetic hybrid (kinetic ions, fluid electrons) simulations, the interaction between solar wind and a magnetized asteroid is investigated. At no or very low levels of asteroid magnetization the solar wind remains undisturbed. As the level of magnetization is increased, a phase standing whistler wake is generated which owing to its propagation characteristics remains confined to planes close to that containing the solar wind flow velocity and the interplanetary magnetic field (IMF). No density perturbations are associated with this wake. Further increase in asteroid magnetization results in the additional generation of fast and slow magnetosonic wakes, which fall behind the whistler wake and are associated with the formation of a plasma tail. Because of their propagation characteristics, these wakes are more symmetric than the whistler wake. At still higher levels of magnetization where plasma pileup occurs upstream of the asteroid, the fast magnetosonic wake becomes dominant and eventually exhibits shock‐like behavior. In general, the size of the interaction region increases with the level of asteroid's magnetic field strength. This interaction region is highly structured and asymmetric owing to wave propagation characteristics and the IMF direction. In addition, once the fast magnetosonic wake is strong enough to result in ion reflection the subsequent E × B motion of these ions results in considerable asymmetry in the interaction region. This is a purely ion kinetic effect which comes about as a result of the overall interaction region being comparable to ion scale lengths.

ビル屋上建造物による電磁波の回折特性の解析

Estimation of the scattering of electromagnetic waves by buildings and other obstacles is very important for wireless communications in urban areas. In this paper, the electric fields of the waves, which are transmitted from one side of a building to travel over its rooftop to reach the other side were calculated on the basis of the GTD including slope diffraction for the cases where rooftop obstacles are and are not present. The fields as diffracted by a square obstacle and a conductive plate on a rooftop of a building are also discussed. The numerical results show that most of the diffracted waves that travel along the rooftop surface are slope-diffracted, and that installing a conductive plate of suitable height on the building's rooftop is a fairly effective way of improving the received level of electric field strength.

Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.

Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms. This is one of several efforts being made by the FDA, the electronic medical device industry and the EAS industry to mitigate the potential for EMI between EAS and medical devices.