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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/m2 and of 2.6 x 10-2 mW/m2 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. Keywords: Sierpinski Antenna; Patch Antenna; CW Doppler Radar; Respiration Rate; Heartbeat Rate

A brief history of mass nature is presented, including formulas for mass variation with velocity V. A new mass hypothesis (MH), on the nature of mass m is presented. Accordingly, the mass m0 of submicroparticle (SMP), is given by the kinetic energy accumulated inside the SMP, by the vortices/vibrations of groups of ether (ETH) cells, constituting the submicroparticles (SSMP). These SSMPs will also create the inertial force (FI) of the SMP, due to the opposition manifested by ETH, toward any accelerated movement of SMP. A new explanation of mass m increase, with V is proposed, admitting the existence of ether in the form of our model, HM16. The entrainment of the surrounding ETH of SMP, takes place, with speed VETH, which stores the EETH energy. The spatial variation of VETH around the SMP, was analysed using the method of potential motions, for a cylinder, moving in water-like fluid, or in ETH, resulting a spectrum of the lines of current ψ, indicating the size of VETH, rapidly decreasing with distance r. So resulted the kinetic energy EETH stored by the movement of the outer ETH, which provides the supplementary mass ms. The case of SMP which acquires velocity V, approaching c, was analysed. Then, a phase change (PC) will take place, through which the SMP, transforms into photons (PHs), when movements of the ETH from the outside including energy EETH is transferred into PH photons, having velocity c, representing ETH’s property.

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.

Article continues and complements our previous articles on the HM16 ether (ETH) model. Here, we describe the mechanism of occurrence of the submicroparticle (SMP). A general hypothesis, HFVI, is introduced for the modalities of interaction between two SMPs, based on periodic mechanical percussion forces, produced by fundamental vibrations FVs. A mechanism for describing the interaction between a SMPs and the ETH is presented. Positive and negative particles are defined by their membrane types of movement, such as +, −u/+, −v vibrations, and rotations at speeds +Ω/−Ω. The process of creating a pair of SMPs is discussed. Applying HFVI to the interaction between pairs of SMPs immobile in ETH, and considering longitudinal FVL, was obtained the forces of attraction/repulsion +FL21/–FL21, which correspond to the completed Coulomb force FCC including gravitation. The resultant FRL21 will form an oriented field of forces, which is a quasielectric field QE, equivalent to actual E electric field. Considering transversal FVT, was obtained the vibratory forces +, −FT21, whose resultant forms an vibrating field of forces, QHs, a quasimagnetic special field, which may explain some of the quantum properties of SMPs. Considering a mobile SMP, two new γ strains in ETH appear. Strains γL are created by the displacement of SMP with velocity V, whose force +, −FT12 is the support of a component of the magnetic field H (quasimagnetic field QH), giving the QHL component. Strains γR are created by the rotation of SMP with speed Ω, whose force +, −FR12 constitutes physical support of the component QHR of magnetic field H (i.e. QH). The creation of a photon PH is modelled as a special ESMP containing two zones of opposed rotations, and a mechanism is presented for its movement in the ETH with speed c based on the HS hypothesis of screwing in ETH, with frequency ν.

The fifth generation (5G) of mobile communication technology poses lots of questions while introducing significant improvements compared with previous generations. The most sensitive question is related to the safety of human exposure. The aim of present work was to analyze, with a few chosen examples, two of the most significant features of 5G emissions: the extreme spatial variability of the exposure and the nonlinear dynamics characteristics of the temporal variability of the exposure. Two models of patch antenna arrays operating at 3.7 GHz with varying beam forming and beam steering capabilities were considered for an analysis of the specific absorption rate of electromagnetic energy deposition in tissues of a head model. This allowed clear emphasis on the influence of the antenna geometry and feeding peculiarities on the spatial variability of exposure. The second approach implemented the original idea of following the nonlinear recurrence behavior of exposure in time, and underlined the time variability characteristics of emissions with a real-life mobile phone running different 5G applications. Time series of the emitted electric-field strengths were recorded by means a real-time spectrum analyzer and two near-field probes differently positioned in the beam. The presence of laminar emissions, chaotic emissions, determinism and recurrence in the exposures prove the potential for recurrence quantification in predicting time variability features of 5G exposure. Overall, the impact of 5G signals on living bodies, with the highest possible man-made spatial and temporal variability, may have very unpredictable bio-medical consequences.

We have approached user exposure to EMF originated from an IEEE 802.11ax client (mobile phone) by using both broadband and frequency selective measurement instrumentation. All the measured field strengths were situated below the ICNIRP and IEEE reference levels for public safe exposure. Higher field levels were observed during file upload followed by file download and then video streaming. Following, we propose an original algorithm for similarity evaluation of the two measurement system readings based on cross-correlation and dynamic time warping (DTW) algorithm. We observed clear differences between probes in general, and between their ability to correctly follow the field strengths amplitude time dynamic. The proposed algorithm offers a series of advantages compared to traditional response time investigation. While the temporal response of the used broadband field probe appears to be adequate for 802.11ax signals, the amplitude resolution exhibits a serious drawback for measuring low field levels associated with some Wi-Fi applications like video streaming.

In this article we propose the use of the persistence spectrum to accurately assess the user’s exposure to electromagnetic field emitted by new generation of communication terminals. Persistent display view available within a Real Time Spectrum Analyzer (RTSA) enables a graphical observation of the main statistical parameters of a signal. A simple case study of exposure assessment was conducted by measuring the electric field strength in the close proximity of a mobile phone operated in a LTE-Advanced mobile communication network. The proposed measurement procedure is presented and then applied to a limited number of operating situations (VoIP, Video streaming, File upload, File download). We made use of the persistence spectrum capabilities to directly access the signal strength statistics in time. By this procedure we demonstrate a supplementary facility that enables direct visual tracing of exposure dynamics during real time usage of a specific mobile application.

In this study, we demonstrate the correctness of our 2010 hypothesis regarding the need to complete Coulomb’s FC law with the term lnr, resulting in the completed FCC force. For this purpose, we consider the electrical interactions between charged microparticles (MPs), which develop as fundamental vibrations (FVs) in ether, producing the vibrational strains e and γ and the resulting stresses σ and τ, as percussions of ether cells (ECs) upon the MP surface. The stresses σ and τ produce a resultant force FP, due to the percussions which constitute the real electric force FCC. The spatial effect of ether on FP is demonstrated by an analytical method, considering the electrical interaction between MPs through various equidistant spatial paths li of FVs, modelled on the basis of the Huygens principle for waves. For this issue, we utilized a numerical calculation, which could be generalized. But this spatial effect of the ether leads at a very slow decreasing of the FP forces ratio rF when doubling the distance l, in contrast to Coulomb’s FC forces whose ratio rF decreases accentuate with doubling l. Accordingly, the necessity of including the term ln r in the FCC force, which is limited to 1.0 for doubling l, at long distances, was justified.

In the present article we propose a solution based on Software Defined Radio for isotropic, real-time, and simultaneous measurement of six channels corresponding to six field probes (electric and magnetic). The measurement system is much needed for exposure evaluation campaigns conducted in the near field of emitting devices (mobile phone, WLAN router, etc.). However, the use of an SDR pose other problems that need careful and precise solving, to report accurate field levels. To this extent, in this work we present the calibration of an instrument model USRP N310 in the n78 5G (3.5-3.7 GHz) frequency band. The instrument response is investigated for a 5G-like signal, namely a 20 MHz wide, LTE-A, OFDM signal. The instrument sensitivity is analysed in function of the used channel bandwidth and compared to a mid-range swept spectrum analyser sensitivity. The frequency and amplitude response of the instrument are commented on. Results suggest suitability of the instrument for the proposed measurement system. To increase the accuracy of the measured field levels a quick frequency response calibration is indicated before each measurement campaign.

Frequencies higher than 3 GHz are today of extreme interest for the agile human exposimetry. Current approach proposes and demonstrates the capability of a statistic method to report 4G/4G+ wireless applications usage impact on the human factor by providing results regarding: a) energy density accumulation rate in air near the emitting device (instantaneous and average); b) observation of peculiarities of time-distribution of emitted field strengths during certain wireless application/device/network/moment in time of usage.

Wi-Fi network devices emit electromagnetic radiation which is of interest for human exposure safety. Based on the quasi-stochastic time-variability of such signals emitted in two different protocols belonging to the 4th and the 5th generations, namely IEEE 802.11 - n and ac, we demonstrate here that specific temporal patterns can be extracted from the time series, if we use the representation of Poincare plots. Practically, the main parameters of the Poincare ellipses are different for the two communication protocols, directions of data transmission and bandwidths used. When energy density per transferred bit was computed, it was also revealed that there is a linear relationship between this one and the Poincare ellipse area. Based on the mean electric field strengths measured near a Wi-Fi device by directly collecting the amplitude probability density traces of the emitted powers, one can extract the features of short- and long-term exposure profile variations in different wireless data transmission configurations.

Increasing the data transfer rate in the High Frequency (HF) range involves enlarging the bandwidth of the channel from the standard value of 3 kHz to values of 6, 12, 24, 48 and even 96 kHz. Real-time evaluation of the noise power in the channel under such conditions is essential. This paper aims to implement an automated system for real-time measurement of noise in the HF range. It is composed of two Software Defined Radio (SDR) synchronized receivers and two orthogonal Inverted Vee antennas. Testing the system demonstrates its ability to distinguish between noise and signals generated as a result of human activity. Preliminary results of measurements performed in an urban location are comparable to other measurements performed and to ITU-R Recommendations P.372 examples.

The Paper highlights discovery from 2000 of two Errors (ERM81/87) by Michelson in analysis of his experiments ME81/87. ERM81/87 has also been addressed in series of previous articles by the authors. ERM81/87 consisted of assuming the transverse path of light ray 2 or of SW2 swimmer, to be an isosceles triangle (Error 1) inclined with angle β’ in referential frame (RF) ether/water (E/W), or a double orthogonal path (in RF device/bank (D/B)), thus calculating the wrong result, t2 < t1, or Δt = t1-t2 > 0, (Error 2), states SW2 wins the contest. In ERM81/87 it is proven firstly, by Demonstration 1, based on logic, starting from the non-observance in Michelson’s analysis, of rules of correctness and fair play, in development of the two swimmers contest (TSC). Rresulted in correct transversal path as a right triangle, with t2 = t1 (in RF, E/W), the correct contest result is a draw. Demonstration 2 consists, in correction of SW2 route, resulting under fair play conditions, for transversal path, a right triangle with hypotenuse inclined at angle 2β (in RF, E/W) and t2 = t1 or Δt = 0, with the contest result in a tie. Demonstration 3 is based on a new Generalised Case (GC) of the TSC where the orientation of the starting path of SW1 can be inclined at any angle α, always one obtains, t1 = t2, the correct result. Evidence provided shows Michelson designed his interferometer by analogy with TSC, Michelson considered SW2 the winner. Evidence provided in 1892 by Lorenz expressed doubts about the correctness of Michelson’s analysis of ME81/87, without finding errors. We show, an initial error (ERM81) was committed by Michelson in ME81analysis, erroneously superposing paths for SW2 (in RF, D/B), and in incorrect calculations of t2 and Δt obtaining t2 < t1, an error communicated to him by Potier, which also mentioned the correct result Δt = 0, without any demonstration. In analysis of ME87, Michelson acknowledged the error, modified the path of SW2 to isosceles triangle (in RF, E/W), and made new t2 calculation. But he reduced by only half, the Δt compared to Δt in ME81, meaning the basic error in Δt (ERM87) has persisted, until today. We emphasize that errors ERM81/87 in TSC are repeatedly printed, and appear in all college physics textbooks around the world, exemplifying by presenting four such excerpts from college textbooks from the US and Canada. Thus, a correction of ERM81/87 is required, starting with the correction of the TSC, by admitting the correct result of equality of SW1 and SW2, in all college physics textbooks. As result the ether can be reintroduced into physics with multiple consequences including re-evaluation of the Special Relativity Theory.

In this paper, we present a new physics theory that offers some explanations of physical phenomena in nature, including some that have remained unexplained to date. Our New Physics Theory 2016 (NPT16) is based on a new model of the ether called HM16. The ether was eliminated from physics in 1905 by Einstein, through his Special Relativity Theory (SRT), based on experiments carried out in 1881/87 by Michelson (ME81/87). We reintroduce the ether to physics as a result of two errors that we have discovered in Michelson’s analysis of his experiments ME81/87. We initially proposed the development of NTP16 in 2016, and we now present an actualised, up-to-date form of NPT16. NPT is the result of taking into account the special properties of ETH ether, which in the HM16 model is characterized by its composition, as a deformable elastic body, without friction, so without energy consumption/loss. ETH consists of compact ether cells EC, which transmit the fundamental vibrations FVs of ECs, created by microparticles MPs, constituted as energy concentrations in their own vortices/oscillations, energy that creates even the mass m of MP. Longitudinal and transverse FVs vibrations, are transmitted between MPs and between ECs, by mechanical percussion pi, specific to the current positive or negative electric charge of an MP. And gravity is the result of the interaction forces FDC between the dipoles, so-called electric, but created by a Coulomb type force FCC, between two MPs completed with a term in lnr. And at astronomical distances, there is a ratio R = FDC/FN ≈ 1.60, which indicates the presence of an increase in the real mass of the stars, of about +60%, compared to the mass considered by gravitational Newton force FN, a result that can explain/replace the current fictitious dark matter. The NPT also gives a physical explanation of the phenomenon of increasing the mass of a material body MB, as its speed V increases. This speed V, leads to an accumulation of energy around MPs, stored in the ECs vortices of ETH around MP, created even by the V-speed motion of the MP. And the energy accumulated around the MP is added to the MP’s own energy, which is even the mass of the MP thus increased.

By applying a non-standardized methodology and by using electric- and magnetic-field probes of small dimensions (< 1cm), we experimentally characterized the electromagnetic shielding properties of a fabric containing ferromagnetic microwires weaved on a single direction. Electronic microscopy and X-ray spectroscopy revealed the structure, dimensions and chemical elements content of the amorphous magnetic material. Electric shielding factor proved to be very low in the investigated frequency range, but magnetic shielding factor was high, especially when the weaving direction of the magnetic wires corresponded to the polarization direction of the emitting antenna, and showed some resonances. The magnetic shielding efficiency, if checked against an increasing incident magnetic flux density, proved not to change up to 200 nT. The investigated fabric have been previously proved to be very efficient in shielding the field emitted by a mobile phone in its near field, but present results show that near and far field shielding properties are different.

A portable radiocommunication device usually face-held during its use was chosen for characterizing its electromagnetic near-field distribution in air. Set to emit on a frequency of 440 MHz for digital voice communication with a maximum input power of 5 W, its antenna parameters were analyzed and the maps of field strengths were depicted up to distances of 20 cm from the device by using of a dual-sensor exposimeter. Since the occupational exposure safety limit for incident field levels was exceeded closer than 12 cm from the transceiver (for the magnetic field component), it became interesting to quantify the power loss in an alleged case of a brain containing also magnetite particles. Up to the present, only the electric field component was of interest when investigating biological effects of such exposures. With the new evidence from 2016, that human brain contains four orders of magnitude more magnetite nanocrystals than it was known before, a question rises in connection to the magnetic response of tissues impinged by fields with significant magnitudes and covering the hundreds of MHz frequency range. Starting from this question, we set-up a simulation in which a tissue with ferromagnetic content was mimicked for initial dosimetric computations

The article initially reviews various works describing the physical model (PM) of Michelson’s interferometric experiment (ME), represented by the race between two swimmers Sw1, Sw2 (or boats, or planes, or sound signals, etc.). The two swimmers must each swim the same distance, but Sw1 will swim along the river flow, and Sw2 will swim perpendicularly to this direction. In all such works, it is considered that Sw2’s path will require less time and that it will reach the start point first. However, in this work, it has been determined that in order to make this possible, Sw2 must not observe the orthogonality rule of his start direction. This action would be deceitful to the arbiters and thus considered as non-fair-play towards Sw1. The article proves by swimming times calculus, that if the fair-play rules are observed, then the correct crosswise path (in water reference frame) is a right triangle instead of the isosceles triangle considered by Michelson. Consequently, the two times shall be perfectly equal and the race ends in a tie, and the myth of Sw2 as the race winner shall be debunked. Note that the same result shall also be applicable to Michelson’s interferometric experiment (ME) as well as to any similar experiment. Therefore, utilising the isosceles triangle as the transversal path in PM and also in ME is an erroneous act.

Here, we initially introduced and demonstrated two principles: orientation OR principle and attraction AT principle of electrical dipoles. The OR principle stipulates that any two electrical dipoles P1A, P1B, from two bodies A and B, at any distance in the free state each, will be reciprocally oriented parallel and in the same sense if the electrical interaction forces F between them are of decreasing type with distance r. If the electrical interaction forces F are of increasing type with distance, the two dipoles will be reciprocally oriented parallel but on the opposite sense. The AT principle stipulate that any two electrical dipoles P1A, P1B, at any distance in the free state each, will present always a reciprocal force of attraction FD in both cases of orientation accordingly to OR principle in case of any type of electrical force F decreasing or increasing with distance. These findings may complete our previous work where we found that FD force, between two electrical dipoles P1A, P1B considered at atomic and nuclear level, is in fact the actual gravitation Newton force FN. The paper must be considered together with this work for more consistency.

A dual band mobile phone model was used to check the shielding properties of an amorphous ferromagnetic textile against the radiation emitted by the handset. Two frequencies belonging to the 2nd and 3rd generation of mobile emission technologies were used, 897 MHz and 1950 MHz. The specific absorption rate (SAR) of energy deposition in a human head phantom was measured in standardized conditions. The textile contained micrometric-diameter wires of a ferromagnetic mixture embedded in a thin glass coat and weaved in a specific way. A set of fabric orientations and configurations (layering) were provided in the experiment in order to achieve a better shielding to the phone’s radiation. Compared with the non-shielded handset, SAR deposited in the head while using the fabric-covered phone could be decreased up to 30 % of its initial value – in case of 2G technology and up to 24 % – in case of 3G technology. This type of material shows one of the highest shielding efficiencies of the electric-field component in near-field exposure conditions reported until now. A cubic curve of SAR decrease in depth of the head was revealed in both uncovered and covered handset, the effect of shielding being larger at the higher frequency.

The measurement of realistic exposure levels of quasi - stochastic signals from the IEEE 802.11ac communication standard was achieved by applying the complementary cumulative distribution function mode of a real - time spectrum analyzer connected to a laptop. Statistics were used to highlight the differences between the data transfer directions.

The paper investigates the accuracy of assessing exposure to radiation emitted by sources specific to the IEEE 802.11n communication standard by two methods. The first one is based on weighing of the maximum power channel measured in the frequency domain and the second one uses the complementary cumulative distribution function (CCDF) acquisition mode of a real-time spectrum analyzer. It has been demonstrated that the CCDF method is much proper to be applied in the case of the quasi-stochastic signals such as WLAN's.

The paper investigates the possibility of using Software Defined Radio (SDR) platforms in assessing exposure to electromagnetic radiation emitted by sources specific to 3G and 4G generations. Critical parameters of SDR platforms that can limit their performance are the sampling frequency and the receiving resolution of the analog to digital converter (ADC). The performed tests showed that the 8-bit ADC resolution has an influence on the amplitude’s dynamic range, i.e. when evaluating exposure to high-level signals (greater than -40 dBm), the accuracy is consistently diminished. The sampling frequency influences the bandwidth of the channel, and broadband signals (e.g. 20 MHz – in case of 4G) impose requirements for the performance of the SDR platform. For an average-priced SDR platform, such as HackRF One, measurements can be conducted with an acceptable accuracy at most on 5 MHz bandwidths.

An analysis of the shielding effectiveness by the method of dual transversal electromagnetic cell is proposed for a set of conductive materials of the type wire-inserted textiles. Based on the experimental results, some of the materials are further on used to test their capability to effectively reduce the specific absorption rate of energy deposition in the head due to mobile phone, when they are covering the surface of the handset. It is demonstrated that both reducing and increasing the radiation that penetrates the head may appear, and this depends on both the material structure, its position and orientation relative to the device and to the frequency band the phone is emitting.

Water-based suspensions of magnetotactic bacteria (MTB) containing magnetite (Fe 3 O 4 ) nanocrystals in the form of magnetosomes (MS) chained inside the bacteria cells have been exposed to radiofrequency fields with the aim of observing how the electromagnetic energy is converted and expressed as thermal or non-thermal effects. A wide frequency band was tested, (0.1-2.9) GHz, by applying continuous wave stimuli. Significant field strength components were provided and characterized, by using a GTEM cell and adequate expo-dosimetric instruments. The heating rates of the suspensions were measured. Because the recorded values were very low, non-thermal expression of energetic conversion was further investigated by scanning-transmission electron microscopy methods, by various spectroscopic means and by electrical conductivity determinations. Clear non-thermal effects were revealed, which need further research.

The paper is focused on the electromagnetic exposure assessment in the proximity of a Terrestrial Trunked Radio (TETRA) terminal. For the first time distinct measurements of the electric field component (E) and of the magnetic field component (H) are presented in the distance range 8-20 cm. The results show that the E-field component has a greater prevalence on the exposure. Maximum values of 100% for E, and 17% for H component respectively were encountered in the near field of the terminal, if compared to the occupational limits given in the ICNIRP protective guidelines.

Magnetotactic bacteria (MTB) cells contain chains of magnetosomes, which are magnetite nanocrystals enveloped in a lipid bilayer. A water-based suspension of cultured MTB was prepared and the electric and magnetic properties were measured by two methods: a reflection method using an open-ended coaxial probe (0.5-50 GHz) and a transmission method using a rectangular waveguide (8.2-12.4 GHz). Based on the very good agreement obtained for the measured complex permittivity of a saline solution with data in the literature, we report here the results of both the complex permittivity and permeability of a suspension of cultured MTB.

In the present work we examine the efficiency of magnetotactic bacteria and biogenic magnetite nanocrystals as potential contrast agents in magnetic resonance imaging. The tests include transverse and longitudinal relaxation measurements on two suspensions of magnetic particles prepared with magnetotactic bacteria and magnetosomes at the same concentration. We observed a strong reduction of the transverse relaxation time by the presence of magnetic particles. On the other hand, only a small influence on the longitudinal time is detected.

A water-based suspension of biogenic magnetite nanocrystals extracted from cultured magnetotactic bacteria was exposed to a set of electromagnetic stimuli in the range (0.1-3) GHz. Controlled exposure was provided and the heating rate of the suspension was measured in each case, providing a comparison between the thermal response of this suspension and pure water, in order to quantify the role of biogenic magnetite in absorbing the electromagnetic field.

Radiocommunications in the HF band depend on the ionospheric parameters of radiowaves reflexion, though the quality of a radio link depends on: the time of day; season; solar cycle; geographical position. Taking into account the ionosphere characteristics over Romania, a forecasting is made over four cities in our country in order to provide the values of the critical frequency foF2 of the F2 ionospheric layer over a 24 hours cycle. A comparative analysis of this parameter is applied by using the International Reference Ionosphere model and interpolated experimental data collected from the European Ionosonde Service. Results show that the f0F2 values are slightly underestimated in all four locations in the model versus measurements, sustaining the necessity of own measurements in order to prepare quality data links in Romania if HF band is to be used for emergency data communications.

The assessment of the exposure levels of humans in areas covered by Wireless Local Area Networks (WLANs) is a complex task. This is mainly due to the quasi-stochastic nature of the signals. With recently developed weighting procedures, realistic results were obtained for the electromagnetic field strength emitted by wireless emitting devices. Present work focuses on three main factors that influence the exposure level and follow their impact on the field strength. The original approach, that of experimental determination of the instantaneous data rate of transmission that is synchronized to the field level reading made by a time–amplitude measurement method, was able to detect some previous erroneous findings – that the duty cycle of transmission is mainly influenced by the data rate and therefore the prediction of the exposure level may be based on the data rate value evolution solely. It is shown here that only a multi-variable analysis based on specific developed experimental techniques is able to provide proper prediction capabilities when it comes to Wireless Fidelity (Wi-Fi) signals behavior in specific environments.

In this paper, measurements of the spectral occupancy in some high frequency (HF) bands in the Western part of Romania are presented. Signals have been acquisitioned by means of an Universal Software Radio Peripheral (USRP) equipment and spectrum occupancy values have been calculated off-line for a set of frequency bands that present interest for establishing of a system for emergency communications. Calculations have been based on an energy detection criterion that is presented and discussed in the paper. Preliminary measurements performed simultaneously at two different locations, namely in Sibiu and Timisoara cities, Romania, are also reported and compared.

The physiotherapeutic use of the pulsed electromagnetic field (PEMF) leads to exposure of patient and any object. Different rules of assessing the influence on humans and electronic devices need to be implemented. The aim was to study the parameters of PEMF emitted by widespread physiotherapeutic devices with respect to the health hazards caused by exposure: by experimental analysis of PEMF waveform and by investigation of the spatial distribution of electric and magnetic field strengths near physiotherapeutic applicators emitting PEMF of the lowest duty factor (Salus Talent, Thermopulse). PEMF was evaluated with respect to root-mean-square (RMS) values averaged in time, or over the pulse duration only, and compared against the limits imposed for the safety of human exposure (general public or workers) and of using electronic medical implants. In measurement results (of RMS value over the pulse duration even exceeding 10-times the RMS values measured over time), the insufficient respond of measuring devices to PEMF (responding not sufficiently fast to pulsed signals, and not sufficiently sensitive to signals of a low duty factor) may reduce measurement results even over 10-times. This may cause a significant underestimation of the hazards caused by PEMF near physiotherapeutic devices (up to 1–2 m from applicators).