IEEE Transactions on Biomedical Circuits and Systems, 2015
With the breakthrough of the Internet of Things and the steady increase of wireless applications ... more With the breakthrough of the Internet of Things and the steady increase of wireless applications in the daily environment, the assessment of radio frequency electromagnetic field (RF-EMF) exposure is key in determining possible health effects of exposure to certain levels of RF-EMF. This paper presents the first experimental validation of a novel personal exposimeter system based on a distributed measurement approach to achieve higher measurement quality and lower measurement variability than the commonly used single point measurement approach of existing exposimeters. An important feature of the system is the integration of inertial sensors in order to determine activity and posture during exposure measurements. The system is designed to assess exposure to frequencies within the 389 to 464, 779 to 928 and 2400 to 2483.5 MHz bands using only two transceivers per node. In this study, the 2400 to 2483.5 MHz band is validated. Every node provides antenna diversity for the different bands in order to achieve higher sensitivity at these frequencies. Two AAA batteries power each standalone node and as such determine the node hardware size of this proof of concept (53 mm×25 mm×15 mm) , making it smaller than any other commercially available exposimeter.
ABSTRACT In this paper a folded cavity-backed patch antenna implemented in substrate integrated w... more ABSTRACT In this paper a folded cavity-backed patch antenna implemented in substrate integrated waveguide (SIW) technology is presented. The antenna has been designed to operate at 2.45 GHz, in the industrial, scientific and medical (ISM) frequency band, and a textile substrate has been adopted for the realization of the component. This topology of textile antenna could be useful for the monitoring of the activities of rescue workers in emergency situations such as the localization of fire-fighters, and the communication in critical operations. The proposed antenna has been experimentally verified: the response of the antenna exhibits a small frequency shift, caused by a discrepancy between the nominal and the real value of electrical permittivity of the textile substrate. The measured radiation characteristics of the antenna show a good agreement with simulations, and a measured radiation efficiency of approximately 70%.
—A reconfigurable layout to implement a self-structuring wearable antenna for the local user term... more —A reconfigurable layout to implement a self-structuring wearable antenna for the local user terminal of a Search and Rescue system (Cospas-Sarsat at 406MHz) is presented. The proposed antenna layout has been designed for integration on a commercial life jacket for use in a maritime environment. The shape of the antenna can be reconfigured by means of RF switches to ensure the best possible transmission conditions, in terms of overall antenna efficiency, even if part of the antenna goes under the sea level. The shape of the components of the self-structuring antenna has been optimized for different antenna positions with respect to the water level and immersion angles.
—Wearable textile antennas are basic components in body-centric communication systems. Flexible w... more —Wearable textile antennas are basic components in body-centric communication systems. Flexible wearable patch antennas, when integrated into a body-worn garment are subjected to bending, causing variation in the resonance frequency when compared to the flat-antenna. Bending conditions vary statistically among different human subjects. Therefore, it is very important to be able to predict performance variations due to bending. We propose novel models which allow to predict the deterministic and statistical variation in resonance frequency of rectangular wearable patch antennas. They consist of an analytical model for cylindrical-rectangular patch antennas, expressing resonance frequency as a function of the bending radius, and a novel technique based on polynomial chaos, that quantifies statistically the variations of the resonance frequency under randomly varying bending conditions. The proposed models have been experimentally and numerically verified, and proven to be much faster and computationally less expensive than traditional techniques based on EM solvers and Monte Carlo simulations, making them very advantageous tools for the design and characterization of body-worn patch antennas.
— In this contribution a novel method is discussed that is of practical use for analyzing the ele... more — In this contribution a novel method is discussed that is of practical use for analyzing the electromagnetic compatibility behavior of electronic systems. The aim is to develop an efficient technique that mimics radiated immunity and emission tests in the presence of multiple non-collocated noise sources in simulation. The proposed method is simple in that it only relies on the simulated (or measured) radiation pattern of the devices in the system while allowing arbitrary positions. Rotation of the devices is performed by a spherical harmonics decomposition of the radiation patterns together with the application of Wigner-D rotation matrices. The adopted assumption is that the devices are spaced sufficiently far from each other such that there is no coupling via the reactive near-field. The proposed procedure shows good agreement with measurements and full-wave simulations while at the same time it has a low computational cost.
IEEE Transactions on Biomedical Circuits and Systems, 2015
With the breakthrough of the Internet of Things and the steady increase of wireless applications ... more With the breakthrough of the Internet of Things and the steady increase of wireless applications in the daily environment, the assessment of radio frequency electromagnetic field (RF-EMF) exposure is key in determining possible health effects of exposure to certain levels of RF-EMF. This paper presents the first experimental validation of a novel personal exposimeter system based on a distributed measurement approach to achieve higher measurement quality and lower measurement variability than the commonly used single point measurement approach of existing exposimeters. An important feature of the system is the integration of inertial sensors in order to determine activity and posture during exposure measurements. The system is designed to assess exposure to frequencies within the 389 to 464, 779 to 928 and 2400 to 2483.5 MHz bands using only two transceivers per node. In this study, the 2400 to 2483.5 MHz band is validated. Every node provides antenna diversity for the different bands in order to achieve higher sensitivity at these frequencies. Two AAA batteries power each standalone node and as such determine the node hardware size of this proof of concept (53 mm×25 mm×15 mm) , making it smaller than any other commercially available exposimeter.
ABSTRACT In this paper a folded cavity-backed patch antenna implemented in substrate integrated w... more ABSTRACT In this paper a folded cavity-backed patch antenna implemented in substrate integrated waveguide (SIW) technology is presented. The antenna has been designed to operate at 2.45 GHz, in the industrial, scientific and medical (ISM) frequency band, and a textile substrate has been adopted for the realization of the component. This topology of textile antenna could be useful for the monitoring of the activities of rescue workers in emergency situations such as the localization of fire-fighters, and the communication in critical operations. The proposed antenna has been experimentally verified: the response of the antenna exhibits a small frequency shift, caused by a discrepancy between the nominal and the real value of electrical permittivity of the textile substrate. The measured radiation characteristics of the antenna show a good agreement with simulations, and a measured radiation efficiency of approximately 70%.
—A reconfigurable layout to implement a self-structuring wearable antenna for the local user term... more —A reconfigurable layout to implement a self-structuring wearable antenna for the local user terminal of a Search and Rescue system (Cospas-Sarsat at 406MHz) is presented. The proposed antenna layout has been designed for integration on a commercial life jacket for use in a maritime environment. The shape of the antenna can be reconfigured by means of RF switches to ensure the best possible transmission conditions, in terms of overall antenna efficiency, even if part of the antenna goes under the sea level. The shape of the components of the self-structuring antenna has been optimized for different antenna positions with respect to the water level and immersion angles.
—Wearable textile antennas are basic components in body-centric communication systems. Flexible w... more —Wearable textile antennas are basic components in body-centric communication systems. Flexible wearable patch antennas, when integrated into a body-worn garment are subjected to bending, causing variation in the resonance frequency when compared to the flat-antenna. Bending conditions vary statistically among different human subjects. Therefore, it is very important to be able to predict performance variations due to bending. We propose novel models which allow to predict the deterministic and statistical variation in resonance frequency of rectangular wearable patch antennas. They consist of an analytical model for cylindrical-rectangular patch antennas, expressing resonance frequency as a function of the bending radius, and a novel technique based on polynomial chaos, that quantifies statistically the variations of the resonance frequency under randomly varying bending conditions. The proposed models have been experimentally and numerically verified, and proven to be much faster and computationally less expensive than traditional techniques based on EM solvers and Monte Carlo simulations, making them very advantageous tools for the design and characterization of body-worn patch antennas.
— In this contribution a novel method is discussed that is of practical use for analyzing the ele... more — In this contribution a novel method is discussed that is of practical use for analyzing the electromagnetic compatibility behavior of electronic systems. The aim is to develop an efficient technique that mimics radiated immunity and emission tests in the presence of multiple non-collocated noise sources in simulation. The proposed method is simple in that it only relies on the simulated (or measured) radiation pattern of the devices in the system while allowing arbitrary positions. Rotation of the devices is performed by a spherical harmonics decomposition of the radiation patterns together with the application of Wigner-D rotation matrices. The adopted assumption is that the devices are spaced sufficiently far from each other such that there is no coupling via the reactive near-field. The proposed procedure shows good agreement with measurements and full-wave simulations while at the same time it has a low computational cost.
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Papers by Hendrik Rogier