Densely populated areas are usually extensively exposed to the emission of electromagnetic fields (EMFs) that is primarily caused due to extensive use of wireless telecommunication technologies, particularly those providing mobile phone communication services. Consequently, observation and control of EMF levels in human surroundings have great importance in terms of human health and environmental protection. Particular efforts have to be devoted to EMF investigation in highly sensitive areas, where people can stay for quite long periods, such as university campuses. This paper brings the results of 2023 EMF monitoring campaign, performed over the University of Novi Sad campus for the third time, comparing them with EMF results obtained in previous 2012 and 2018 campaigns. Having in mind the emergence of new 4G Long Term Evolution (LTE) base stations in the campus, during 2022, a special focus of the 2023 campaign was on the inevitable increase of field levels, because of the contribution of 2G/3G/4G mobile communication technologies to human EMF exposure. Despite the expected increase of the field levels, obtained values were still significantly lower than the minimal reference levels, prescribed by the Serbian legislation.

A uniform magnetic field can be achieved with various simple structures of circular or square cross-sections. The main purpose of each of these is to create a larger volume of uniformly distributed magnetic field. The improvement of the desired zone homogeneity can be achieved by varying the design parameters of the coil and applying different optimization algorithms. In this paper, the Lee-Whiting circular coil system has been investigated considering the cross-section of the real conductor instead of the volumeless ideal conductor. The parameters of the coil were optimized to achieve a uniformly distributed magnetic field inside a spherical area and the desired total deviation rate along the centreline. The numerical calculations and the optimization procedure were performed on a simplified 2D axial symmetric model. The obtained results show that in the case of real conductors, the coil positions differ from the Lee-Whiting arrangement.

This work investigates the temporal statistical structure of time series of electric field (EF) intensity recorded with the aim of exploring the dynamical patterns associated with periods with different human activity in urban areas. The analyzed time series were obtained from a sensor of the EMF RATEL monitoring system installed in the campus area of the University of Novi Sad, Serbia. The sensor performs wideband cumulative EF intensity monitoring of all active commercial EF sources, thus including those linked to human utilization of wireless communication systems. Monitoring was performed continuously during the years 2019 and 2020, allowing us to investigate the effects on the patterns of EF intensity of varying conditions of human mobility, including regular teaching and exam activity within the campus, as well as limitations to mobility related to the COVID-19 pandemic. Time series analysis was performed using both simple statistics (mean and variance) and combining the information-theoretic measure of information storage (IS) with the method of surrogate data to quantify the regularity of EF dynamic patterns and detect the presence of nonlinear dynamics. Moreover, to assess the possible coexistence of dynamic behaviors across multiple temporal scales, IS analysis was performed over consecutive observation windows lasting one day, week, month, and year, respectively coarse grained at time scales of 6 min, 30 min, 2 h, and 1 day. Our results document that the EF intensity patterns of variability are modulated by the movement of people at daily, weekly, and monthly scales, and are blunted during periods of restricted mobility related to the COVID-19 pandemic. Mobility restrictions also affected significantly the regularity of the EF intensity time series, resulting in lower values of IS observed simultaneously with a loss of nonlinear dynamics. Thus, our analysis can be useful to investigate changes in the global patterns of human mobility both during pandemics or other types of events, and from this perspective may serve to implement strategies for safety assessment and for optimizing the design of networks of EF sensors.

In electrical engineering the Earth appears frequently as a media of conducting currents. In order to protect humans of electrocuting, the utilities chassis are usually grounded, the lightning rods are grounded as well and sometime the Earth is applied as a return conductor. For that reason, it is necessary to investigate the Earth's behavior when it is used as a conducting media. The best way to do this investigation is to determine the current distribution within the Earth. .

The method for the temperature measurement on the surface of three copper conductors, with cross-sections of 4 mm2 , 6 mm2 i 10 mm2 , are presented in this paper. After the determination of temperature probe, the series of temperature measurements are performed on chosen wire conductors. The first two series are performed applying DC generator, in two different cases: when, during the measurement the voltage on the conductor’s end was held constant and the current inside the conductor was held constant. After that, the temperature measurements on the conductor’s surface were performed supplying conductors with AC, time harmonic currents, again in two particular cases: constant RMS voltage value on the conductor’s ends and constant RMS value of current inside the conductor. The measuring results were expected for all four cases and for all thee conductors. Due to presence of skin effect, the Joule’s losses were higher in the AC cases, meaning that the temperature increase was faster and that the final reached temperature, for the same values of voltage or currents, was higher. It was also demonstrated that the higher Joule’s losses appeared when the current was kept constant during the measurements, in both DC and AC supplying. The measurements were performed with the instrument which enabled the results recording on USB stick; hence the measurements duration was 30 minutes, recording result every two seconds. The measuring results were presented graphically, together with graphical presentation of the comparison between methods and the results for all investigated conductors.