Geometrical Theory of Diffraction Formulation for On-Body Propagation

Kammersgaard, Nikolaj P. B.; Kvist, Søren H.; Thaysen, Jesper; Jakobsen, Kaj Bjarne

doi:10.1109/tap.2018.2882596

Cited by 12 publications

(5 citation statements)

References 29 publications

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“…The propagation model on which this work is built is presented in detail in [5] and [7]. Here, a few of the principles and components of the model are repeated for convenience.…”

Section: Theory and Propagation Modelmentioning

confidence: 99%

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Ear-to-Ear Propagation Model—Antenna Radiation Pattern Optimization

Nielsen

Kvist

Jakobsen

2023

2023 17th European Conference on Antennas and Propagation (EuCAP)

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A highly sophisticated ray-based propagation model is used to find the optimal on-body radiation pattern for an earto-ear link. The propagation model allows for a rapid evaluation of the path gain given the antenna radiation patterns. The radiation patterns are represented by the spherical wave expansion (SWE) since they are easy to handle in the computer and in addition the expansion coefficients separate one antenna from another. Furthermore, the SWE produces physically realizable radiation patterns. The procedure to obtain the optimal radiation patterns is formulated as evolution-based optimization. It is found that the optimal gain pattern directs the power in the directions of the geodesic paths traced by the model that lead from one ear to the other. This is in accordance with expectations. The optimized path gain is -35.0 dB, which is obtained with lossless antennas with a minimum sphere of 0.2 free-space wavelengths.

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“…The propagation model on which this work is built is presented in detail in [5] and [7]. Here, a few of the principles and components of the model are repeated for convenience.…”

Section: Theory and Propagation Modelmentioning

confidence: 99%

“…1. The electromagnetic losses experienced by a creeping wave as it propagates along one of the geodesic paths, is evaluated according to the theory presented in [7] based on a geometrical theory of diffraction (GTD) formulation. Each ray is then weighted by the correct gain and phase of the simulated ear antenna.…”

Section: Theory and Propagation Modelmentioning

confidence: 99%

Ear-to-Ear Propagation Model—Antenna Radiation Pattern Optimization

Nielsen

Kvist

Jakobsen

2023

2023 17th European Conference on Antennas and Propagation (EuCAP)

Self Cite

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“…It should be mentioned here that at microwave frequencies around 2.4 GHz the component of the electric field that is perpendicular to the surface of the body contributes predominantly to the energy transfer, cf. [16]. Thus, only this component is required in the evaluation of the path gain in Eq.…”

Section: Theory and Model Descriptionmentioning

confidence: 99%

Ear-to-Ear Propagation Model—Comparison of Free-Space and On-Body Gain Formulations

Nielsen

Kvist

Jakobsen

2023

2023 17th European Conference on Antennas and Propagation (EuCAP)

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Two different formulations of the antenna far-field used to evaluate the on-body path gain at 2.45 GHz through a raybased ear-to-ear propagation model are compared. The free-space far-field formulation does not take field coupling to the human body in the on-body far-field into account, whereas the on-body formulation does. The simulations are compared with a reference full-wave simulation. It is expected that the on-body formulation should improve the accuracy of the propagation model since it takes the field-to-body coupling into account in the on-body farfield. It is found that the results of the comparative study are aligned with expectations. The path gain that results from the use of the on-body far-field formulation is closer to the reference path gain in the band of interest, i.e., around 2.45 GHz.

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“…On‐body channels are defined between communication nodes on or above the skin of limited height and are usually restricted over short distances, for example, 1–2 m. An on‐body channel is jointly formed by near field propagation and body scattering effects [3], leading to complex electromagnetic (EM) field distribution on the skin. This propagation mechanism is also modelled by surface wave or creeping wave assumption where the on‐body propagation path is defined on the skin surface, allowing the radio waves to travel around the body [4].…”

Section: Introductionmentioning

confidence: 99%

Performance analysis and optimization of polarized on‐body relay channels

Liu

Jin

Zhang

et al. 2021

IET Microwaves Antenna & Prop

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On-body propagation channels show significant polarization selectivity that has dominant impacts on the on-body link quality in wireless body area networks. For on-body relay channels over long distances across the body, the antenna polarization configurations of the relaying nodes are crucial to determine the relay performance, thereby requiring polarization optimization schemes. In this article, narrow band flat-fading on-body channels at 2.484 GHz are measured to analyse their polarization distribution above the skin under static postures. The measured on-body channels show full-space polarization convergence and dispersion, which are modelled by an extended 3 by 3 channel polarization matrix, and a statistical channel model is also proposed. Multi-hop polarized on-body relay channels are analysed on the relay link capacity, which shows polarization dependency between adjacent hop channels when relaying nodes are mounted by linearly polarized antennas. Both regular and iterative polarization selection algorithms are then designed to optimise the antenna polarization configuration of the nodes. Simulations based on the proposed polarization distribution model show significant link capacity increases for two-hop and tfhree-hop on-body relay channels by the optimization algorithms. The results confirm the necessity of proper polarization selection schemes for onbody relay channels.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Geometrical Theory of Diffraction Formulation for On-Body Propagation

Cited by 12 publications

References 29 publications

Ear-to-Ear Propagation Model—Antenna Radiation Pattern Optimization

Ear-to-Ear Propagation Model—Antenna Radiation Pattern Optimization

Ear-to-Ear Propagation Model—Comparison of Free-Space and On-Body Gain Formulations

Performance analysis and optimization of polarized on‐body relay channels

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