Electromagnetic models for the optimization of body-centric antennas
Final Report Abstract
The particular challenge for modeling body-worn and/or implanted (on-body) wireless systems lies in the near-field coupling of the antenna and the dissipative tissue. Hence, so far the antennas could not be considered separately from the propagation channel in the system description. Therefore, methods for the systematic antenna development of on-body applications were developed in the project, whereas the antennas are characterized separately. First, a method for characterizing on-body antennas was developed based on physical modeling of the propagation along the tissue. Furthermore, on-body antenna parameters were derived, which represent an adapted form of the standard free-space antenna parameters. Secondly, a method for modeling on-body links based on spherical wave functions was developed. It enables obtaining separate models of the antennas and the channel at a higher level of abstraction. Since the developed on-body antenna parameters were defined closely to the standard free space definitions, an intuitive characterization of on-body antennas is possible. Furthermore, a measurement system was developed for assessing the defined antenna parameters for physical prototypes. For applications with the channel not significantly affected by body postures, it is possible to perform link budget calculations directly based on the on-body antenna parameters and a newly defined on-body Friis equation. The developed method based on spherical wave functions complements the modeling capabilities concerning dynamic channels, as the antenna performance can be efficiently evaluated in many different channel models. Furthermore, the channel model is determined numerically, thus, no geometrical simplifications are necessary. Beyond the characterization of on-body antennas and channels, the design of optimized antennas for these applications presents a substantial challenge. For applications with channels classified as approximately static, optimization can be done directly from the on-body antenna parameters by maximizing the on-body antenna gain in the direction of the main propagation path. This is not possible for dynamic channels. Therefore, antenna optimization based on SWF modeling was also developed. With this, optimal characteristics of the antenna can be calculated based on many different possible channel models. To obtain a possibility for metrological validation here, both developed methods were linked with each other, so that a determination of the on-body antenna parameters is also possible based on the (optimal) SWF coefficients. Through example applications, developed methods could be validated to allow an efficient modeling as well as a targeted design of body-worn and/or implanted antennas.
Publications
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(2019), “Evaluation of Bannisters Subsurface-to-Air Model for Implanted Antennas”, 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - AP-S/URSI, 2019
S. Meshksar, L. Berkelmann and D. Manteuffel
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"Antenna Parameters for On-Body Communications with Wearable and Implantable Antennas," IEEE Transactions on Antennas and Propagation, Volume: 69, Issue: 9, pp. 5377-5387, September 2021
Berkelmann, Lukas & Manteuffel, Dirk
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"On-Body Antenna Radiation Pattern Measurement System," 2021 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2021, pp. 031-031
Berkelmann, L. & Manteuffel, D.
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Antenna Optimization for WBAN Based on Spherical Wave Functions De-Embedding
L. Berkelmann, H. Jäschke, L. Mörlein, L. Grundmann and D. Manteuffel
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„Implantable Antenna Design for Surface-Wave Based In-Body to On-Body Communications,” 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - AP-S/URSI, 2021
Berkelmann, Lukas & Manteuffel, Dirk
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"Characterization of Wearable and Implanted Antennas: Test Procedure and Range Design," IEEE Transactions on Antennas and Propagation
Berkelmann, Lukas & Manteuffel, Dirk
