Analytic on-body antenna and propagation models

authored by
Markus Grimm
supervised by
Dirk Michael Manteuffel
Abstract

The use of wireless communication technologies for the intercommunication of body-worn applications is increasing rapidly nowadays. In accordance with the ongoing miniaturization of wearable devices, the interaction between the antenna and the user becomes more and more intense. As a result of the inability of the traditional free-space antenna theory to describe the excitation of on-body surface waves, this has so far led to insufficient insights into the development of such body-centric systems. Hence, the aim of this thesis is to derive on-body antenna parameters and physically motivated EM propagation models that can be used to develop scalable path gain models as well as optimized design strategies. Considering planar dissipative surfaces, an intuitive propagation model is discussed, which follows the classical Sommerfeld problem. An appropriate solution for quasi-static ranges is adapted and consulted to discuss basic principles of electromagnetic propagation of on-body line-of-sight scenarios for selected frequencies between 400 MHz and 60 GHz. Based on these results, an antenna de-embedding is introduced in the course of this thesis, which is capable of modeling the average radiated antenna far field. Furthermore, a decomposition of the total on-body far field into a TM field component and a TE one is discussed to define two equivalent electric dipole sources. This approach enables the definition of the on-body directivity as well as the effective antenna area to discuss the radiation properties of the corresponding antenna geometry in terms of on-body communications. While this approach is primarily limited to line-of-sight propagations, a cylindrical dielectric phantom is introduced to cover non-line-of-sight links as well. In this case, the introduced de-embedding method is used to model the quasi-static range while the bended propagation path is treated by an adapted cylindrical model, which emphasizes the TM/TE-related far field decomposition of the planar model. Finally, the theory that is derived is verified by numerical full human body examples as well as by measurement setups in an anechoic chamber.

Organisation(s)
Institute of Microwave and Wireless Systems
Type
Doctoral thesis
No. of pages
146
Publication date
2019
Publication status
Published
Electronic version(s)
https://doi.org/10.15488/4317 (Access: Open)
 

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