Development of antenna arrays for terrestrial and satellite applications: Feasibility study of different solutions to monitoring the atmospheric pollution, determination of electromagnetic fields in urban scenario and calculation of their dosimetry in small animals

The present work can be summarized as it follows: First of all, it will be held theoretical and numerical studies to improve the performance of antenna arrays by focusing on the isophoric case. Then, different antenna designs are shown and discussed, in order to be integrated within the urban environment. Some of these designs are experimentally tested. On the other hand, a study on the characterization of the electromagnetic fields through urban areas based on an equivalent planar circuit model is highlighted. Moreover and lastly, the influence of the electromagnetic fields in small animals is discussed by using two methods for the SAR level determination

An Improved Pattern Synthesis Iterative Method in Planar Arrays for Obtaining Efficient Footprints with Arbitrary Boundaries

In the present paper, an iterative technique devoted to reproducing efficient footprints with arbitrary boundaries for planar arrays is addressed. The methodology here depicted is based on exploiting the nature of the continuous aperture distribution by expressing it as a Fourier series of moderately high orders. In this manner, the resulting illumination boundary is defined by a target three-dimensional flat-topped pattern composed of stretching and shrinking modified circular Taylor patterns and the maximum order of the series to obtain a good reconstruction is determined by means of the iterative process. Examples and comparisons with the previous literature were conducted by analyzing square and rectangular contoured beams as test cases. Additionally, interesting potentials regarding space applications from a geostationary satellite are outlined by means of the EuTELSAT (European Telecommunications Satellite Organization) European coverage case study. In such a way, its numerical approach was analyzed by including subarray architectures and discussing improvements about dynamic range ratio of the excitations without critical power losses within the illumination regionThis work was supported in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación under Project TEC2017-86110-R. The work of A.A.S.S. is supported by the Xunta de Galicia Postdoctoral Fellowship with reference ED481B 2018/008S

Validation of Potential Effects on Human Health of in Vivo Experimental Models Studied in Rats Exposed to Sub-Thermal Radiofrequency. Possible Health Risks Due to the Interaction of Electromagnetic Pollution and Environmental Particles

Studies are based on the exposure of Sprague–Dawley rats (250 male and 250 female rats) to electromagnetic fields (EMF) at different frequencies in standing and travelling wave chambers. Values of specific absortion rate (SAR) for all of these experiments were obtained from commercially available FDTD-based simulation software based on numerical phantom animals. An experimental radiation system was developed with a standing-wave cavity which keeps electromagnetic parameters constant while facilitating stress-free exposure of animals to non-thermal radiation. This makes it possible to directly measure the power absorbed by the animal and determine whole-body mean SAR according to weight. All studies using this setup were performed with global system for mobile communication (GSM) radiation at 900 MHz. The simple picrotoxin model made allow to identify morphological signs of neurotoxicity in rat brain tissue. Experiments involving travelling waves were done in a commercial Gigahertz Transverse ElectroMagnetic (GTEM) chamber connected to one or two vector signal generators (to carry single or multiple EMF exposure frequencies). In the diathermy model, rat thyroid and thymus exposed to 2.45 GHz radiation showed visible morphological and immune effects. Cellular stress in the cerebral cortex, the cerebellum or both seems to be more associated with the type of signal than with additive effects of combined frequencies. Finally, some hypothesis related with the future models about the ElectroMagnetic (EM) pollution are established. In an urban environmental that combines the electromagnetic and chemical pollution of environmental particles, cortical excitability, inflammatory response, and cell injury can be modified.This work was supported in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación under Project TEC2017-86110-RS

Feasibility Study on Measuring the Particulate Matter Level in the Atmosphere by Means of Yagi–Uda-Like Antennas

In this work, the application of a technique for monitoring changes of the dielectric constant of the atmosphere caused by the presence of pollution is discussed. The method is based on changes in the reflection coefficient of the device induced by these dielectric constant variations of the surrounding medium. To that end, several Yagi–Uda-like antenna designs with different size limitations were simulated by using a Method-of-Moments software and optimized by means of a simulated annealing strategy. It has been found that the larger the optimal elements of the array are allowed to be, the higher the sensitivity reached. Thus, in a trade-off between sensitivity and moderate length (regarding flexibility purposes), the most promising solution has been built. This prototype has been experimentally tested in presence of an artificial aerosol made of PAO (polyalphaolefin) oil and black carbon inclusions of a size of 0.2 μm. As a result, potentials for developing a measurement procedure by means of changes in the characteristic parameters of the antenna led by different concentration levels of suspended particles in the surrounding medium are shown. In this manner, a local mapping of polluted levels could be developed in an easy, real-time, and flexible procedureThis work was supported in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación under Project TEC2017-86110-R. The work of A.A.S.-S. is supported by the Xunta de Galicia Postdoctoral Fellowship with reference ED481/008S

Multiple Solutions Starting from Real Shaped Beams in Equispaced Linear Arrays

In the present work, the theoretical basis of the multiplicity of solutions obtained from an initial real symmetric distribution is derived. This initial solution is devoted to generating an equivalent pure real shaped-beam pattern for a concrete synthesis scenario. However, these new solutions are not based on real symmetric distributions; hence, not based on the generation of pure real patterns. The bandwidth performances and tolerance to errors provided by the multiple solutions in the array design are analyzed by considering different architectures, also including mutual coupling models and element factor expressions due to accuracy purposes. In addition, a technique to obtain efficient linear arrays by designing resonant structures is addressed. Examples involving both standard linear arrays of half-wavelength cylindrical dipoles and resonant linear arrays generating flat-top beam patterns are reported and discussed. Additionally, an extension to planar arrays performed by means of a generalisation of the Baklanov transformation through collapsed distribution techniques inspired in the well-known method devised by Tseng and Cheng is performed. In such a way, an analysis of the quality of solutions for generating circular and elliptical footprints with controlled both SLL and ripple which are highly interesting in the framework of space vehicle applicationsThis work was supported in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación under Project TEC2017-86110-R. The work of A.Á.S.-S. is supported by the Xunta de Galicia Postdoctoral Fellowship with reference ED481B 2018/008S

Antena de guía de ondas ranurada para uso como medidor de concentración de polutantes en el ambiente: estudio de viabilidad y optimización numérica

An optimized antenna design based on waveguidefed slot linear array antennas for measuring the polluted air level in the atmosphere is proposed. This device is based on the differences in terms of the environmental dielectric constant due to different particulate matter concentrations. Because these variations, it would be possible monitoring this pollution level due to changes in the performance of the antenna. The optimization process and some simulations results are presente

Improvement of Edge Brightening by Means of Q Factor Minimization in Circular Antenna Apertures: High Efficient Taylor-Like Patterns

Implications and improvements of edge brightening effects led by Q factor minimization restricted to keep the same level of directivity for high efficiency continuous circular aperture distributions are here reported. In this manner, an optimization strategy for a minimum Q value-keeping the same level of efficiency and restricting the maximum sidelobe level (SLL)- is envisaged. As application of the method, a design procedure devoted to reduce the Q factor of the antenna aperture distributions while keeping a high level of efficiency is outlined. Then, these optimal Taylor distributions are used as initial point to develop an optimization strategy. This procedure is devoted to search Taylor-like distributions which offer a good compromise between low Q factor and high efficiency values with potentials for the antenna design scenario, based on a decrease in edge brightening effects led by the minimization of the aforementioned Q ratioS

Estudio de viabilidad para la medición de la humedad relativa mediante antenas de dipolo con recubrimiento de poliimida

Relative humidity alters the dielectric coefficient of polyimide. This could allow us to measure its effects on the performance of a dipole antenna. Here we report the results of simulations suggesting that this is a feasible method of monitoring relative humidity in the ai

Exposure to 2.45 GHz Radiation Triggers Changes in HSP-70, Glucocorticoid Receptors and GFAP Biomarkers in Rat Brain

Brain tissue may be especially sensitive to electromagnetic phenomena provoking signs of neural stress in cerebral activity. Fifty-four adult female Sprague-Dawley rats underwent ELISA and immunohistochemistry testing of four relevant anatomical areas of the cerebrum to measure biomarkers indicating induction of heat shock protein 70 (HSP-70), glucocorticoid receptors (GCR) or glial fibrillary acidic protein (GFAP) after single or repeated exposure to 2.45 GHz radiation in the experimental set-up. Neither radiation regime caused tissue heating, so thermal effects can be ruled out. A progressive decrease in GCR and HSP-70 was observed after acute or repeated irradiation in the somatosensory cortex, hypothalamus and hippocampus. In the limbic cortex; however, values for both biomarkers were significantly higher after repeated exposure to irradiation when compared to control animals. GFAP values in brain tissue after irradiation were not significantly different or were even lower than those of nonirradiated animals in all brain regions studied. Our results suggest that repeated exposure to 2.45 GHz elicited GCR/HSP-70 dysregulation in the brain, triggering a state of stress that could decrease tissue anti-inflammatory action without favoring glial proliferation and make the nervous system more vulnerableThis work was supported in part by the FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación under Project TEC2017-86110-R. The work of A.Á.S.-S. is supported by the Xunta de Galicia Postdoctoral Fellowship, reference ED481B 2018/008. The financial support of the Tunisian Ministry of Higher Education and Scientific Research is gratefully acknowledgedS

Análisis comparativo de SAR y estrés en animales pequeños en dos sistemas de radiación de onda viajera y de onda estacionaria a 900 MHz

Exposure to non-ionizing electromagnetic radiation is increasing every day through mobile phones. In this experiment we try to find the influence of this exposure in twenty-four Sprague-Dawley rats brain when radiation is caused by a GTEM chamber (travelling wave chamber) and by a stationary wave chamber. Both chambers are irradiating at frequency of 900 MHz. The experimental system consisted of a vector signal generator, a directional coupler, a power meter and the two enclosures (working separately) where the animal was immobilized by a methacrylate holder. In order to determine the radiation effects, rectal thermal measures are performed to calculate the SAR (Specific Absorption Ratio) values in the brain. We performed a comparison between the radiation dosimetry, compared the stress levels of the animals and finally we studied the neuronal activation with immunohistochemistry test c-fos in the brain of animals exposed to radiation in both chambers. We found that a GTEM chamber gives lower values for the average SAR than a stationary wave chamber. Stress levels in animals are higher in the cavity standing wave than in the GTEM. Postmortem neuronal activation in the brain appears with a different pattern: unilateral in traveling wave and bilateral in standing-wav