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.
In this study, electromagnetic shielding e ectiveness of ceramic bodies produced with natural zeolite illuminated by an electromagnetic pulse is investigated. A matrix model is used to calculate the propagation of electromagnetic pulse through sample. Shielding e ectiveness of sample is determined for both transmitted electric and magnetic elds. Mathematical theory of the interaction and the shielding e ectiveness of the sample is determined as a function of frequency, thickness of the material and the incidence angle of electromagnetic pulse. Zeolites used in this study were supplied from ETI Holding Company located in Turkey. Water was added as a binder and disc samples were shaped by uniaxial dry pressing at pressing pressure of 1.5 tone. Samples were red in an electric furnace with a heating rate of 10 • C/min at 1150 • C with a period of 60 min. Electrical measurements are performed to determine the dielectric constant and dielectric loss tangent at 25 • C constant temperature between frequency range from 1 kHz up to 2 MHz.
Determination of the levels of the electromagnetic field of frequency between 0 Hz and 300 GHz bands in the working area and the evaluation of the results measured in terms of international standards is now essential according to the regulation of working safety and health. In this study, electromagnetic field measurements were performed in a cleaning product manufacturing factory with 400 workers. Electric and magnetic field measurements were performed at 10 different departments of the factory with extremely low-frequency and broadband (radiofrequency) frequencies. Obtained values are shown and analysed with graphs and compared by the International Commission on Non-Ionizing Radiation Protection and National Information Technology and Communication Authority (Turkey) limits. Also, an assessment is made for the occupational electromagnetic field levels in the factory and recommendations are suggested for the lowest risk occurrence and providing a healthier working environment for workers.
The purpose of the paper is to analyze and simulate the shielding effectiveness (SE) performance of a fiber reinforced cylindrical shell. A matrix model is presented to evaluate the transmitted electromagnetic fields on the axis of cylindrical shell. SE performance of the cylindrical shell is calculated for various parameters such as radius of cylinder, shell thickness and shell conductivity. Also, a 3D model of the cylindrical shell is constructed via Computer Software Technology (CST) program to carry out the analytical results. The analytical calculations and simulations are performed for TM mode excitation. A good agreement is obtained by the comparison of analytical results and CST simulations.
The metal skin of air vehicles provides an important shielding effectiveness against the effects of high amplitude electromagnetic waves. In recent years, the composite materials with the advantages such as being lighter, causing lower fuel consumption, are used as a replacement of metals. In this paper, electromagnetic shielding performance of composite materials in air vehicle manufacturing industry is investigated. A panel model is used to obtain the shielding performance of these composite materials. Due to the geometrical similarity of air vehicles with a cylinder, a cylindrical shell model is also considered. Analytical calculations for the interaction of an electromagnetic pulse(EMP) with composite materials are carried out for both panel and cylindrical models. Also, the panel and cylindrical models are constructed via Computer Software Technology(CST) program and analytical and simulation results are compared. There is a good agreement with the results.
In this study, the design and electrical tests of polarization-independent radar absorber fabric containing an array of circular shaped conductive patches positioned on a neoprene fabric are presented. The proposed absorber has an overall thickness of 1.57 mm and a unit cell dimension of 8.75 × 8.75 mm 2 , which is < λ/3, where λ is the free-space wavelength at 9.33 GHz. In the designs, electrical performance of the radar absorber fabric is numerically studied in both planar and conformal structures. Furthermore, the two-dimensional (2D) surface current distribution at the resonant frequency is examined to better understand the operating principles of the proposed structure. Finally, a prototype of the radar absorber is manufactured using neoprene fabric with relative permittivity of 3.18, loss tangent of 0.93, and the frequency dependent reflection parameter values are measured by using the free space measurement technique to validate the numerical results. A good agreement between the measurement and numerical results is obtained.
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