Characterizing the time variations of signals emitted by mobile terminals provides complementary information to health authorities, especially with the increase of frequency and energy of radiation towards millimeter waves. This experimental work aimed to quantify and classify the time variability of the electric field level measured at 10cm from a mobile phone connected sequentially to a 4th and 5th generation mobile network. Statistic analysis was performed on data from real-time spectrum analyzers, while self-similarity was computed by first recurrence plots of the radiated emissions, corresponding to five different types of mobile applications. Moreover, specificities to the communication standard and the type of application were identified.

<abstract> <p>Realistic human exposures to radiation emitted by a mobile terminal connected to either a 5G network (sub-6 GHz) or to a 4G network have been scarcely assessed till now. Present experimental work aimed at comparing the radiated field in air, in a single point situated at 10 cm from a mobile phone when running a set of 5 mobile applications in the two communication standards. The time-evolution of the electric field strength in air near the terminal during 25 s of use was recorded by an original method, together with the data rate of transmission. The emitted power density dynamics, its statistics, its slope of accumulation after the usage period and its average value per transmitted bit are analyzed and compared between all the situations. The peculiarities are emphasized and they are proved to depend on the communication standard and on the mobile application.</p> </abstract>

The paper proposes the use of MATLAB simulations as a first step in identifying proper antennas to be used in specific ultra-high frequency (UHF) communication links. Giving that fractal antennas provide interesting features, we aimed at comparing a few of their significant parameters with those of a monopole antenna so as to ensure signal coverage between two real sites situated at 5.82 km distance in a mixture of urban and flat – open terrain conditions. We started from the requirements imposed to the return loss of the antenna and to the link margin, we established their desired thresholds and then computed solutions regarding which antenna type in the set provide the highest received power and on which frequency sub-bands can be successfully used. The studied fractal antenna set were from the series Koch, Koch loop and Sierpinski. The chosen radio link refers to a real situation on the map. Generally, different narrow bands were provided by each antenna regardless of its type, but still, comparing them with the monopole, better solutions could be identified.

Objectives: To fabricate planar models of antennas with resonance frequencies in the ultrahigh frequency band that allow short-range detection of respiration and heartbeat by a simple continuous wave Doppler radar system. Methods: Models of antennas were created in CST Studio software and the main parameters were computed. Then, antennas were fabricated at a PCB prototyping machine and were experimentally characterized in an anechoic chamber. Total efficiency and radiation patterns indicated the best working frequencies of 2.12 GHz and 8.82 GHz respectively, to test the human vital signs detection with a continuous-wave Doppler radar technique in direct visibility conditions. Findings: The patch antenna at 2.12 GHz had a maximum gain of 3.15 dBi and total efficiency of 43% while the Sierpinski antenna at 8.82 GHz had a maximum gain of 5.5 dBi and total efficiency of 65%. At incident power densities on the human subject's chest of 4.5 x 10 -4 mW/m 2 and of 2.6 x 10 -2 mW/m 2 respectively, the Doppler radar system based on these antennas offered precise responses. Practically, it was possible to extract both the heartbeat rate and the respiration rate, by simply applying the classical FFT algorithm on a time-series phase data of the transmission coefficient recorded during 30 seconds, when the set-up was composed of just the antennas and a vector network analyzer. Novelty: Increased detection accuracy was obtained due to careful characterization of the antennas parameters with no need of special processing algorithms.

The growing evidence of increased magnetite nanoparticles (both endo- and exo-genic) in the human brain raises the importance of assessing the entire power deposition when electromagnetic waves at GHz frequencies propagate in such tissues. This frequency range corresponds to many popular portable communication devices that emit radiation close to a human's head. At these frequencies, the current dosimetric numerical codes can not accurately compute the magnetic losses part. This is due to the lack of an implemented computational algorithm based on solving the coupled Maxwell and Landau-Lifshitz-Gilbert equations, in the case of magneto-dielectrics, considering eddy currents losses and specific properties of magnetic sub-millimetric particles. This paper focuses on analyzing the limits and the inconsistencies when using commercial dosimetric numerical software to analyze the total absorbed power in brain models having ferrimagnetic content and being exposed to 3.5GHz electromagnetic waves. Magnetic losses computed using Polder’s permeability tensor as constitutive relation lead to unreliable results. However, using such software can provide a preliminary view of the electromagnetic impact of ultra- and super-high frequencies on magnetic-dielectric tissues.