Installation Uncertainty of Field Level Calculation around a Base Station Antenna

In the near field, the antenna pattern provided by the antenna manufacturer is generally not applicable, or should be considered with caution, even for the single antenna in free space. In the real life, antenna is often surrounded by other conductive objects in the immediate vicinity. These objects tend to distort the antenna radiation pattern. Since the electromagnetic field calculation for the coverage or radiation hazard analysis depends on the three-dimensional antenna gain, this effect should be taken into account. This paper suggests the use of "installation uncertainty" that should be added to the field calculation. The amount of this quantity depends on the installation geometry and can be calculated numerically for a specific situation. This paper shows the results of numerical calculations for some typical antenna installation geometries

Usporedba djelovanja mikrovalnog zračenja frekvencija 864 MHz i 935 MHz na stanice u kulturi

The objective of this study was to compare the effects of 864 MHz and 935 MHz radiofrequency/microwave radiation on the ability of V79 cells to proliferate, form colonies and on their viability. For one, two and three hours, the cells were exposed to the 864 MHz field in a transversal electromagnetic mode cell (TEM) connected with amplifier and to the 935 MHz field in a gigahertz transversal electromagnetic mode cell (GTEM) equipped with a signal generator. The average specific absorption rate (SAR) was 0.08 W kg-1 for the 864 MHz field and 0.12 W kg-1 for the 935 MHz field. In comparison to the control cell samples, the growth curve of the 864 MHz irradiated cells showed a significant decrease after two-hour and three-hour exposure on the Day 3 after exposure. Likewise, cells exposed to 935 MHz microwaves for three hours showed a significant growth on Day 3 after exposure. The colony-forming ability and viability of cells exposed to 864 MHz and 935 MHz microwaves did not significantly differ from the matched controls. The applied RF/MW fields showed a similar effect on cell culture growth, colony-forming ability and viability of V79 cells.Cilj istraživanja bio je usporediti utjecaj 864 MHz i 935 MHz mikrovalnog zračenja na stanični rast, sposobnost stvaranja kolonija (CFA) i vijabilnost trajne kulture V79-stanica. Prethodno pripremljeni uzorci stanične kulture izlagani su 1, 2 i 3 sata određenim mikrovalnim poljima. Za frekvenciju 864 MHz upotrijebljena je transverzna elektromagnetska komora (TEM komora) opremljena generatorom i pojačalom signala. Polje frekvencije 935 MHz stvoreno je s pomoću gigahercne transverzne elektromagnetske komore (GTEM komora) i generatora signala. Prosječna vrijednost specifične brzine apsorpcije (SAR) iznosila je 0.08 W kg-1 za 864 MHz te 0.12 W kg-1 za 935 MHz.. Stanice su rasle u standardnim laboratorijskim uvjetima (>80 % vlage, 37 °C, 5 % CO2). Za određivanje krivulje staničnog rasta V79-stanice su nasađene u koncentraciji od 1x104 mL-1 hranjivog medija. Iz početne koncentracije od 200 nasađenih stanica sedam dana nakon ozračivanja određena je CFA za svako vrijeme izloženosti brojem nastalih staničnih kolonija. Vijabilnost stanica određena je nakon 1, 2 i 3 sata izloženosti RF/MW poljima s pomoću tripanskog plavila. Vijabilnost je utvrđena omjerom živih i mrtvih stanica tijekom 5 uzastopnih dana pokusa. Rast stanica izloženih 2 i 3 sata polju frekvencije 864 MHz bio je značajno inhibiran treći dan nakon izlaganja, a polje frekvencije 935 MHz je u trosatnoj izloženosti uzoraka uzrokovalo značajan pad broja stanica samo trećeg dana. CFA i vijabilnost stanica izloženih poljima od 864 MHz i 935 MHz nisu se značajno razlikovale od odgovarajućih sham izloženih uzoraka. Mikrovalna polja spomenutih osobina djelovala su na gotovo istovjetan način na rast stanične kulture, sposobnost stvaranja kolonija i vijabilnost V79-stanica

Measurements of Antenna Parameters in GTEM Cell

The paper presents the method for measuring parameters (gain, antenna factor, impedance and radiation pattern) of small antennas in GTEM cell, which is a novel method and environment for antenna measurements. In order toinvestigate the suitability of GTEM cell for this kind ofmeasurement, the measurement results for a biconical dipole, microstrip patch antennas and small loop antenna were compared with those obtained by calibration inside fully absorber lined anechoic site, two-antenna measurements and FEKO simulations. The measurements were carried out over the wide frequency range. Measurement setup was limited to small antennas that fit into the usable test volume of the GTEM cell. Different sizes that satisfy this restriction were examined. The GTEM measurement results showed considerable agreementwith compared results

Radiation Hazard Aspect of Shipboard Radiocommunication Equipment

The paper analyzes the electromagnetic (EM) radiofrequency (RF) radiation hazards onboard a ship arising from shipboard radiocommunication and navigation equipment. EM field effect on personnel and equipment can be harmful if field levels exceed the threshold values. These fields need to be controlled for proper protection. Ships are equipped with lots of EM RF radiation sources with different frequencies and output power levels. Typical shipboard EM RF radiation sources include: terrestrial radiocommunication transmitters, navigational radars and satellite ship earth stations (SES). Examples of these sources are analyzed in the paper. EM field estimation using simple worst-case calculation is given for a typical HF transmitter, X-band navigational radar and the Inmarsat SES A, B, C, F and M. The estimation problems are discussed. The calculation results are compared with international civil and military standards. The results show that potential hazards exist and that a reasonable amount of caution is needed

Simulation and Measurements of Electric and Magnetic Fields of an RFID Loop Antenna Anti-Theft Gate System

The radiation of RFID anti-theft gate system based on two parallel coaxial square loop antennas has been analyzed.The system was simulated in FEKO and near electric andmagnetic fields have been calculated. A physical model of thesystem was realized and near magnetic field was measured.Measurement results were found to be in excellent agreementwith the simulation. The obtained simulation and measurementresults have been compared to the exposure limits given asreference levels in the ICNIRP guidelines. No violation of limitshas been shown, regarding both occupational and publicexposure

Radiating Slot in the Coaxial Cable Shield: Measurement Based Characterization

The paper presents the comprehensive experimental study of radiation characteristics of a single slot in a coaxial cable shield. The slot was realized in four different embodiments, which varied by slot orientation and length. Three orthogonal polarizations of radiated electric field were analyzed along the axis perpendicular to cable, broadside to the slot, in a broadband frequency range (80-1000 MHz). The analysis was based on thorough measurements of the coupling loss, which is the common parameter for the leaky cable characterization. The obtained results showed that the electric field component longitudinal to the cable axis considerably dominates over other two orthogonal components, for all four slot types. Doubling the length of the slot caused a ca. 20 dB increase of the radiated field. Different slot orientations, having the same length in the cross-section projection, yielded approximately equal field strengths. The results of this experimental study clearly and visibly demonstrate the radiating slot field dependence on polarization and slot geometry in a wide frequency range. Thus they are useful for planning of wireless communication systems based on radiating cables, as well as for understanding polarization related issues in such systems

Computation of SAR in Human Eye and Pregnant Woman Using Different Simulation Tools

Electromagnetic modeling of large scale problems arising from complex geometries, such as the human body or the specific organ, is generally undertaken by numerical methods implemented in simulation software packages. The structures involving high discretization density (mainly based on Magnetic Resonance Imaging and handled by Finite Difference Time Domain method) consume tremendously high computational cost. On the other hand, oversimplified numerical models may result in significantly less accuracy. The aim of this work was to investigate how detailed numerical model could be created using standard personal computer. Two rather complex cases of exposure were analyzed: human eye and pregnant woman exposed to radiofrequency electromagnetic radiation. The SAR distribution, peak localized 10g-averaged SAR and volume-averaged SAR in these models were determined using two software packages based on different numerical methods: FEKO software based on Finite Element Method and SEMCAD X software based on Finite Difference Time Domain method. The obtained results were compared to the results arising from other scientific studies which included the models of different complexity solved by different numerical methods

Current Directions in the Auricular

Electrical stimulation of the auricular vagus nerve (aVNS) is an emerging electroceutical technology in the field of bioelectronic medicine with applications in therapy. Artificial modulation of the afferent vagus nerve – a powerful entrance to the brain – affects a large number of physiological processes implicating interactions between the brain and body. Engineering aspects of aVNS determine its efficiency in application. The relevant safety and regulatory issues need to be appropriately addressed. In particular, in silico modeling acts as a tool for aVNS optimization. The evolution of personalized electroceuticals using novel architectures of the closed-loop aVNS paradigms with biofeedback can be expected to optimally meet therapy needs. For the first time, two international workshops on aVNS have been held in Warsaw and Vienna in 2017 within the scope of EU COST Action “European network for innovative uses of EMFs in biomedical applications (BM1309).” Both workshops focused critically on the driving physiological mechanisms of aVNS, its experimental and clinical studies in animals and humans, in silico aVNS studies, technological advancements, and regulatory barriers. The results of the workshops are covered in two reviews, covering physiological and engineering aspects. The present review summarizes on engineering aspects – a discussion of physiological aspects is provided by our accompanying article (Kaniusas et al., 2019). Both reviews build a reasonable bridge from the rationale of aVNS as a therapeutic tool to current research lines, all of them being highly relevant for the promising aVNS technology to reach the patient.European Cooperation in Science and TechnologyThe Austrian Research Promotion Agenc

Modulation impact on measurement error of wideband electric field probe for health hazard estimation

U disertaciji se analizira širokopojasna mjerna sonda za mjerenje jakosti električnog polja koja se zasniva na diodnoj detekciji napona induciranog na kratkom dipolu. Ovakva sonda se koristi za mjerenje jakosti polja u svrhu procjene utjecaja na ljude, te je svaka pogreška mjerenja važna. Analiza je pokazala značajne pogreške pri mjerenju jakog polja s moduliranom ovojnicom. U disertaciji je objašnjen uzrok nastanka ove pogreške, te su izvedene jednadžbe kojima se granice iznosa pogreške mogu predvidjeti za različite valne oblike upadnog električnog polja.This PhD thesis analyzed the wideband electric field probe. The probe measures the field by diode detection of the voltage induced on a short dipole antenna. Since this kind of probe is commonly used for human health hazard estimation, every amount of error is extremely important. The analysis showed severe errors when strong electric field with modulated envelope is measured. The cause of this measurement error was explained and its boundaries were calculated by analytical equations, for various incident field waveforms

Modulation impact on measurement error of wideband electric field probe for health hazard estimation

U disertaciji se analizira širokopojasna mjerna sonda za mjerenje jakosti električnog polja koja se zasniva na diodnoj detekciji napona induciranog na kratkom dipolu. Ovakva sonda se koristi za mjerenje jakosti polja u svrhu procjene utjecaja na ljude, te je svaka pogreška mjerenja važna. Analiza je pokazala značajne pogreške pri mjerenju jakog polja s moduliranom ovojnicom. U disertaciji je objašnjen uzrok nastanka ove pogreške, te su izvedene jednadžbe kojima se granice iznosa pogreške mogu predvidjeti za različite valne oblike upadnog električnog polja.This PhD thesis analyzed the wideband electric field probe. The probe measures the field by diode detection of the voltage induced on a short dipole antenna. Since this kind of probe is commonly used for human health hazard estimation, every amount of error is extremely important. The analysis showed severe errors when strong electric field with modulated envelope is measured. The cause of this measurement error was explained and its boundaries were calculated by analytical equations, for various incident field waveforms