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The Human Body Antenna: Characteristics and its Application
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... For example, in the work of [3], measurements of in-body channel in the 13.5 MHz ISM band are realized to reliably transmit one bit to signal an emergency condition. Moreover, the traditional HBCs, especially the capacitive coupling implementation, are not well confined to the human body, so the signal may be easily detected, leading to secure issues [102]. Therefore, it is necessary to investigate whether on-body communications can be achieved at higher frequencies to realize higher data rate, more reliable, and more secure wireless communications. ...
The aging of population and the increase in medical costs have brought a lot of innovations in the medical domain. One of them is the use of wireless sensors that are located in, on, or around the human body to monitor patient’s physiological signs. Due to the nature of the transmitted data, high data security is one of the most essential requirements in the system. The first objective of this thesis is to improve the communication security between on-body sensors with a novel transmission mechanism that uses human skin as a transmission medium and confines the surface-wave signal inside the skin. Transverse resonance method (TRM) is used to numerically analyze existing modes within the human body model. Confinement capabilities as well as propagation losses are investigated for frequencies up to 60 GHz. It should be noted that the developed TRM-based dispersion analysis code is the core work of this thesis and is used throughout all the main analysis in this thesis. Another innovation in the medical domain can be referred to the non-contact sensor-less remote medical monitoring using Doppler radar. Leaky-wave antennas are good candidatures for such applications due to their frequency-depending beam scanning properties. A fast scanning is desired in order to cover a large angular range with a given operation frequency bandwidth. Consequently, in the second part of this thesis, an original TRM-procedure-based design is proposed to increase the frequency dispersion of the guiding structure, which uses a grounded dielectric slab covered by a metasurface. Using this enhanced dispersion, a periodic leaky-wave antenna is designed and simulated in the 60 GHz band.
International guidelines and standards on whole-body radio-frequency (RF) dosimetry use the Whole-Body Averaged Specific Absorption Rate (WBA-SAR) as a surrogate metric to quantify the temperature rise in the body. This study proposes the analysis of whole-body RF dosimetry for far-field exposure of a grounded human body in the frequency range of 1-150 MHz based on a semi-analytic approach of cylindrical antenna theory. The human body is represented by a lossy homogeneous cylindrical monopole antenna. For the first time, an explicit model for the resonance frequency of a grounded human body is proposed. The model captures the effects of the human body weight, height and the dielectric properties. This study also addresses the effect of shoes on WBA-SAR. It is found that the resonance frequency for the WBA-SAR with shoe effect is higher than reported from using the bare-footed models, as confirmed by theory and measurement.
This paper, for the first time, fully characterizes the human body as a monopole antenna in the frequency range of 10 - 110 MHz, which contains the resonance frequency of the human body. The human body is represented by an equivalent cylindrical monopole antenna grounded on a highly conductive ground plane that is analysed based on the three-term approximation method. The reflection coefficient is measured using a human subject as a monopole antenna.Measurement results show that the theoretical predictions are in reasonable agreement. It is found that the human body resonates between 40 - 60 MHz depending on the posture of the body when it is fed by a 50 impedance system at the base of the foot. A minimum reflection coefficient of -12 dB is measured that demonstrates that the human body can be potentially used as an antenna. Theoretically, it is predicted that the human body can be an efficient antenna with a maximum radiation efficiency reaching up to 70 %, which is supported by measurement results found in the literature.
This study proposes an accurate estimation of whole-body averaged specific absorption rate (WBA-SAR) for far-field exposure of an isolated human body in the frequency range of 10-200 MHz based on a lossy homogenous cylindrical antenna model of the human body. Equations are derived for the total induced axial current and the whole-body averaged SAR based on a rigorous treatment of cylindrical antenna theory. An explicit formula for the resonance frequency in terms of the anatomical parameters and the dielectric properties of the body is proposed for the first time. Moreover, important phenomena in far-field radio frequency (RF) dosimetry, such as, the cause of resonance and the SAR frequency characteristics are discussed from an antenna theory perspective.
A unique text on the theory and design fundaments of inductors and transformers, updated with more coverage on the optimization of magnetic devices and many new design examples The first edition is popular among a very broad audience of readers in different areas of engineering and science. This book covers the theory and design techniques of the major types of high-frequency power inductors and transformers for a variety of applications, including switching-mode power supplies (SMPS) and resonant dc-to-ac power inverters and dc-to-dc power converters. It describes eddy-current phenomena (such as skin and proximity effects), high-frequency magnetic materials, core saturation, core losses, complex permeability, high-frequency winding resistance, winding power losses, optimization of winding conductors, integrated inductors and transformers, PCB inductors, self-capacitances, self-resonant frequency, core utilization factor area product method, and design techniques and procedures of power inductors and transformers. These components are commonly used in modern power conversion applications. The material in this book has been class-tested over many years in the author's own courses at Wright State University, which have a high enrolment of about a hundred graduate students per term. The book presents the growing area of magnetic component research in a textbook form, covering the foundations for analysing and designing magnetic devices specifically at high-frequencies. Integrated inductors are described, and the Self-capacitance of inductors and transformers is examined. This new edition adds information on the optimization of magnetic components (Chapter 5). Chapter 2 has been expanded to provide better coverage of core losses and complex permeability, and Chapter 9 has more in-depth coverage of self-capacitances and self-resonant frequency of inductors. There is a more rigorous treatment of many concepts in all chapters. Updated end-of-chapter problems aid the readers' learning process, with an online solutions manual available for use in the classroom. Provides physics-based descriptions and models of discrete inductors and transformers as well as integrated magnetic devices New coverage on the optimization of magnetic devices, updated information on core losses and complex permeability, and more in-depth coverage of self-capacitances and self-resonant frequency of inductors Many new design examples and end-of-chapter problems for the reader to test their learning Presents the most up-to-date and important references in the field Updated solutions manual, now available through a companion website An up to date resource for Post-graduates and professors working in electrical and computer engineering. Research students in power electronics. Practising design engineers of power electronics circuits and RF (radio-frequency) power amplifiers, senior undergraduates in electrical and computer engineering, and R & D staff.
Dynamic-type sea-water monopole antenna of high efficiency is presented by using a new shunt-excited feeding structure. The shunt-excited feeding structure is mainly formed by a conducting tube and a Gamma-shape (Γ-shape) feeding arm connected to the conducting tube near the top. An equivalent circuit model and ANSYS HFSS software are used in the analysis and design of the sea-water monopole antenna. In order to verify the validity of our design concept, two prototypes of shunt-excited sea-water monopole antennas are designed and fabricated: static-type and dynamic-type. Measured results of the two fabricated antenna prototypes are in reasonably good agreement with simulated ones, which demonstrates that the proposed shunt-excited feeding structure offers a great potential for designing high-efficiency dynamic-type sea-water monopole antennas.