Wydział Elektrotechniki, Elektroniki, Informatyki i Automatyki / Faculty of Electrical, Electronic, Computer and Control Engineering / W2
Stały URI zbioruhttp://hdl.handle.net/11652/2
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Pozycja Knitted shields against electromagnetic waves(Wydawnictwo Politechniki Łódzkiej, 2022) Mikołajczyk, Zbigniew; Nowak, Iwona; Szewczyk, Monika; Januszkiewicz, Łukasz; Junak, JoannaThe purpose of the research is to counteract the negative impact of electromagnetic waves on the human body by using knitted textile barriers. Four variants of knitted fabrics with plain weft stitches were designed and manufactured from electrically conductive yarns with resistance of 490 ohms. The variants of the knitted fabrics differed significantly in structural parameters, including loop density – varying from 15 to 0.9 thousand loops and fabric cover from 64 to 33%. The barrier properties against reflected waves at frequencies from 2 to 7 GHz ranged from 10 to 64 dB. It has been proven that shielding effectiveness SE depends on stitch geometry and structural parameters of the knitted fabric. It is a good starting point for further research on the optimization of the performance of knitted barriers against electromagnetic waves.Pozycja Impact of Indoor Environment on Path Loss in Body Area Networks(MDPI, 2014) Hausman, Sławomir; Januszkiewicz, ŁukaszIn this paper the influence of an example indoor environment on narrowband radio channel path loss for body area networks operating around 2.4 GHz is investigated using computer simulations and on-site measurements. In contrast to other similar studies, the simulation model included both a numerical human body phantom and its environment—room walls, floor and ceiling. As an example, radio signal attenuation between two different configurations of transceivers with dipole antennas placed in a direct vicinity of a human body (on-body scenario) is analyzed by computer simulations for several types of reflecting environments. In the analyzed case the propagation environments comprised a human body and office room walls. As a reference environment for comparison, free space with only a conducting ground plane, modelling a steel mesh reinforced concrete floor, was chosen. The transmitting and receiving antennas were placed in two on-body configurations chest–back and chest–arm. Path loss vs. frequency simulation results obtained using Finite Difference Time Domain (FDTD) method and a multi-tissue anthropomorphic phantom were compared to results of measurements taken with a vector network analyzer with a human subject located in an average-size empty cuboidal office room. A comparison of path loss values in different environments variants gives some qualitative and quantitative insight into the adequacy of simplified indoor environment model for the indoor body area network channel representation.