Pawel Bienkowski

A New Method For Automated Noise Cancellation In Electromagnetic Field Measurement

Abstract Electromagnetic field (EMF) measurements have limited accuracy, which is additionally impaired by meter self-noise influence. In this paper, a novel noise cancellation method is proposed, based on the Hidden Markov Model (HMM) methodology. It allows us to calculate the overall field intensity with a much higher accuracy than that obtained from other popular approaches, especially when EMF measurements are close to the noise level. The effectiveness of the new method is illustrated on two EMF datasets, one recorded in an urban and the other in a rural area. Its performance is further evaluated in a thorough simulation study using datasets representing the two distinct noisy environments.

Methods of the electromagnetic fields intensity level assessment and monitoring in the environment

The paper contains review of electromagnetic field (EMF) sources from the environmental point of view. It shows the simplest methods of EMF measurement and differences between selective and broadband measurements listing its advantages and disadvantages, what is essential for the EMF assessment for the need of monitoring in the environment. The measurement possibilities are also one of the subject taken up in this work. Authors point an important aspect of EMF evaluation which is field intensity changeability in time (periodicity) characteristic for mobile telephony systems related with the subscribers daily activity.

EMF meters for surveying purposes calibration and validation

The work presents selected problems of calibration, testing and checking the electromagnetic field (EMF) meters and probes designated mainly for measurements in the near-field. The metrology is related to surveying labor safety and environment protection against unwanted exposure to the EMF.

Non-stationary EMF surveying accuracy improvement

The paper discusses accuracy of non-stationary EMF measurements. The accuracy is mainly limited by applied methods of meters calibration. New method of calibration is presented. The method allows a limitation of the calibration inaccuracy to level of ±1dB.

A prototype of pulse electromagnetic field standard setup with envelope shaping

Paper presents a concept of pulse electromagnetic field (PEMF) standard setup with envelope shaping. Analysis of EMF sources with particular pulse envelopes is performed. Authors presented novel approach to build standard setup, that allow to shape envelope of generated PEMF. A prototype and principal of operation was described, two methods of envelope data handling presented and also a preliminary results of prototype testing.

Optimization of measurement methods for a multi-frequency electromagnetic field from mobile phone base station using broadband EMF meter

BACKGROUND 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. MATERIAL AND METHODS 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. RESULTS 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. CONCLUSIONS 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).

Mitigation measures of electromagnetic field exposurein the vicinity of high frequency welders

BACKGROUND Presented information about the welding process and equipment, focusing on the emission of electromagnetic field (EMF) with levels significant in terms of the labor safety regulations in force in Poland - the ordinances of the Minister of Family, Labour and Social Policy that came into force on June 27, 2016 and June 29, 2016 - emerged due to harmonization with European Union directive 2013/35/EU of 26 June 2013 of the European Parliament and the Council. They presented methods of determination of the EMF distribution in the welding machine surroundings and analyzed the background knowledge from the available literature. MATERIAL AND METHODS The subject of the analysis included popular high frequency welders widely used in the industry. Electromagnetic field measurements were performed in the welder operating place (in situ) during machine normal operations, using measurement methods accordant with labor safety regulations in force in Poland and according to the same guidelines, the EMF distributions and parameters having been described. RESULTS They presented various scenarios of particular, real examples of excessive exposure to EMF in the dielectric welder surroundings and showed solutions, ranging from simple and costless and ending on dedicated electromagnetic shielding systems, which allowed to reduce EMF exposure in some cases of more than 80% (protection zone ranges) or eliminate dangerous zone presence. CONCLUSIONS It has shown that in the dielectric welders surrounding, significant EMF strength levels may be the result of errors or omissions which often occur during development, installation, operation or modification of welding machines. It has allowed to present the measures that may significantly reduce the exposure to EMF of workers in the welder surroundings. The role of accredited laboratories in helping in such cases was underlined. Med Pr 2017;68(6):693-703.

Exposure systems used in the assessment of emf impact on living organisms

The subject of the study in the article is the processes of analysis and exposure assessment of electromagnetic field on humans. The main goal is to optimize size of the exposure antenna systems, its electrical parameters and generated electromagnetic field (EMF) for different frequency range. Objectives: Electromagnetic field (EMF – Electromagnetic Fields) studies on living organisms are one of the important branches of biomedical research. Most of this type of research is conducted using dedicated exposures system with fixed and controlled EMF exposure conditions. The purpose of biomedical research is to determine the influence of electromagnetic fields on living organisms. For this purpose the exposure systems are designed. The main task of the exposure antenna system, is to produce the EMF with known and controlled parameters in a specific EMF area. Depending on the frequency and the component (E or H) of the electromagnetic field used, different types of systems are used. For low frequencies (for instance 50 Hz common frequency) and magnetic fields, Helmholtz solenoids or coils are used, and for electric fields flat capacitors (E Field). For higher frequencies field E is used for systems with linear antennas or TEM lines. There are also dedicated probes for invasive tissue heating. Each solution has its advantages and limitations and usually there are no universal solutions for all cases. Results: For the generation of a low frequency magnetic field up to several hundred Hz, the Helmholtz solenoid or coil is generally used because of its relatively simple construction, the ability to obtain high intensity and good homogeneity of the field in a relatively large area relative to the dimensions of the whole system. The homogeneous field area can be determined analytically based on system geometry or measurement. Otherwise it looks for exposure system above few MHZ. To create a homogeneous EMF in the field of radio frequencies, the exposure systems usually the TEM lines (Crawford compartment) or sometimes the GTEM are very likely to be used. In both cases there are frequency and spatial limitations the homogeneous field is assumed to be maximally present. At 1/3 the height between the plates of the chamber and at the same time the maximum frequency of operation of the TEM chamber can be described by the approximate dependence of fmax [MHz] = 50 / d [m], resulting in a chamber operating at 1 GHz. The work piece does not exceed a height of about 1.5 cm with a diameter of about 4 cm. Larger working areas, but at the same time, a lower homogeneity of the field can be obtained in the GTEM chamber but at the same time the GTEM chamber has much larger geometric dimensions. Another way is to produce PEM with the parameters in open space in the vicinity of the antenna. In this case, it is very important to select an antenna so that the expected homogeneous area can be obtained at an acceptable distance from the antenna in order to maintain high EMF intensity and to reduce the radiation of the antenna beyond the desired area. This can be achieved by limiting the emission area by, for example, shielding or using EMF absorbers. In addition authors simulate novel ablation antenna for ablation treatment. Conclusions: Assessing the impact of EMF on biological objects is an interdisciplinary studies that requires the involvement of biological or medical specialists, as well as the EMF standard field and metrology specialist. In this work we have taken the subject of correct selection and description used in the experience of exposure systems. The authors presented the most commonly used EMF emitters in the low frequencies and microwave bands, as well as new model of the ablation treatment antenna.

Alternative method of electromagnetic absorbers quality determination

Work presents basic information about electromagnetic absorbers, its parameters and known methods of its determination - calculations and direct measurement methods. A new simplified and cost-effective method of quality determination is presented, which introduce new quality measure - “Homogeneity Disorder Factor” (HDF). It bounds information about reflectivity with distance from measured absorber on particular frequency. Proper measurements are performed according to presented method and results are presented and discussed.

Electromagnetic field in high frequency welder surroundings

Paper describes the character of electromagnetic field (EMF) distribution in high frequency welder surrounding based on measurements performed for various welding scenarios, depending on material type, layer count and welding parameters. Measurement results were presented, visualized and discussed. Welding process and its parameters were described and also brief description of high frequency welder construction and operation principal was delivered.