Accurate Determination of the Electromagnetic Field Due to WiMAX Base Station Antennas

2008 ◽  
Vol 50 (3) ◽  
pp. 730-735 ◽  
Author(s):  
Wout Joseph ◽  
Leen Verloock ◽  
Luc Martens
Keyword(s):  
Electromagnetic Field ◽  
Accurate Determination ◽  
Base Station ◽  
Base Station Antennas

scholarly journals ANALYSIS ON TRENDING ELECTROMAGNETIC EXPOSURE LEVELS AT HOMES AND PROXIMITY NEXT TO BASE STATIONS ALONG THREE YEARS IN A CITY

2015 ◽  
Vol 23 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Osman ÇEREZCİ ◽  
Baha KANBEROĞLU ◽  
Şuayb Çağrı YENER
Keyword(s):  
Electromagnetic Field ◽  
Base Station ◽  
Base Stations ◽  
Homogeneous Distribution ◽  
Field Exposure ◽  
Limit Values ◽  
Base Station Antennas ◽  
Outdoor Environments ◽  
Exposure Levels ◽  
The City

Electromagnetic field exposure levels of people living in the closest houses to the GSM transmitting antennas were investigated in a city between 2010 and 2012. At the end of 3-year period, trend of the electromagnetic exposure levels was determined especially for indoor/outdoor environments near the base station antennas. Because of increasing number of base stations by years and changing of the technology, it is determined that average electromagnetic exposure values in the city increased in a certain extent each year. Total and frequency selective measurements were performed in indoor/outdoor places. The results were compared by International ICNIRP limits. In addition, possibility of the compliance with some European countries which have applied low limit values are discussed to minimize involuntary exposure to electromagnetic fields at indoor/outdoor environments. Consequently, a suggestion is made and discussed for obtaining relatively homogeneous distribution of electromagnetic field exposure at indoor/outdoor environments near base station antennas to eliminate extent values.

Hygienic strategy of mobile communication base station antennas radiofrequency electromagnetic field values modern control

2020 ◽  
Vol 60 (9) ◽  
pp. 583-586
Author(s):  
Lidia A. Lutsenko ◽  
Anna V. Sukhova ◽  
Rustam V. Turdyev
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Radiation ◽  
Information Technologies ◽  
Rapid Development ◽  
Ground Level ◽  
Base Station ◽  
Base Stations ◽  
Radio Communications ◽  
Base Station Antennas ◽  
Energy Flux Density

Introduction. The urgency of the issue is due to the rapid development of new telecommunications and information technologies, the widespread introduction and distribution of cellular base stations (BS), which changes the conditions of contact of the population with sources of electromagnetic radiation of radio frequencies (EMR RF). The aim of the study is to summarize the results of the analysis of the project documentation for the placement of mobile radiotelephone network BS in terms of comparability of calculated and actually measured levels of electromagnetic radiation (EMR) from transmitting antennas; to determine the prospective tasks of hygienic control of the safety of the BS. Materials and methods. For hygienic control of EMR levels, serial broadband meters PZ-42 and NBM-550 were used; the method according to MUC 4.3.1677-03 "Determination of the levels of the electromagnetic field created by radiating technical means of television, FM radio broadcasting and base stations of land mobile radio communications". 74 BS were examined, whose antennas were a source of EMR at the frequency of 2620-2640 MHz with a power of 24.2-24.4 W. Results. The maximum length of the building restriction zone (BRZ) from the BS antennas ranged from 16 m to 101 m, regardless of the power of the radiating means, in 50% of cases the length of the BRZ was 30-45 m. In 40% of cases, BS antennas are installed on the roofs of low-rise buildings with BRZ at a height that falls to 5-10 meters from ground level. The excess of the calculated EMR values in terms of energy flux density (EFD) was determined for 50% of the BS. Instrumental measurements of EFD in 19.4% of cases showed excess remote, 11.1% - exceeding marked only by considering the expanded uncertainty (EU) measurement EFD. It was found that the values of EFD measured with EU are more closely approximated to the calculated values. Conclusions. Substantiated recommendations on whether the calculation of the era for height and length for the lower lobes in a radiation direction of antenna, recording ratio EU of the measured values of EFD for additional health human in multivariate emitters of EMR RF. The prospective tasks of hygienic control of the safety of the BS operation are defined.

scholarly journals On Actual Maximum Exposure From 5G Multi-Column Radio Base Station Antennas for Electromagnetic Field Compliance Assessment

2021 ◽  
Author(s):  
Bo Xu ◽  
Davide Colombi ◽  
Christer Törnevik ◽  
Fatemeh Ghasemifard ◽  
Jiajia Chen
Keyword(s):  
Electromagnetic Field ◽  
Queuing Theory ◽  
Power Transmission ◽  
Traditional Approach ◽  
Base Station ◽  
Traffic Load ◽  
Field Exposure ◽  
Compliance Assessment ◽  
Base Station Antennas ◽  
Maximum Exposure

The traditional approach of radio frequency electromagnetic field exposure compliance assessment is highly conservative when applied to radio base station antennas implementing dynamic beamforming. In this paper, an analytical model based on the queuing theory with a hyper-exponential service distribution time is developed to assess the time-averaged actual maximum downlink exposure of 5G multi-column radio base station antennas by taking into account the effects of beam scanning over time in free space. Using the measured antenna radiation patterns, the 5G downlink antenna precoding codebook, and assuming a conservative user equipment distribution, the ratio of the actual maximum exposure to the theoretical maximum exposure with 100% traffic load and 75% time-division duplex downlink duty cycle is found to be less than 0.5 and 0.3 for four-transmitter and eight-transmitter radio base station antennas, respectively. These results show that assuming constant peak power transmission in a fixed direction leads to an overestimate of downlink exposure also from conventional antennas characterized by only a few transmitters in addition to massive multi-input multi-output products.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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