Human Monitoring, Smart Health and Assisted Living: Techniques and technologies, 2017
Respiratory rate is a vital parameter of primary importance in medicine, sport/fitness and wellne... more Respiratory rate is a vital parameter of primary importance in medicine, sport/fitness and wellness in general, especially for most vulnerable categories of people like children and elderly people. Contactless determination of breathing activity provides a powerful and essential mean for evaluating this parameter in subjects who cannot accommodate physical sensors on their bodies. In hospital such subjects may be intensive care patients, prematurely born children and hosts of burn units. Moreover, also for long-term measurements of healthy people, for example, an elder living in home alone or in a care centre, invasive systems prove to be uncomfortable and annoying. Even for a night-time diagnosis of respiratory sleep disorders, like apnoea and hypopnoea, they demonstrate to interfere with the sleep regularity. Therefore, in the last decades many electronic devices have been conceived and realized to detect such an important parameter along with different branches of physics: strain gauges, ultrasounds, optics, thermometry, etc. This chapter presents the theoretical studies, the design and realization of a standalone Electromagnetic (EM) system for contactless determination of breathing frequency and subject's activity. Two major EM solutions are already known in the literature, continuous wave (CW) systems, and ultra-wideband (UWB) systems. The first evaluates the Doppler effect caused by the chest displacement during breathing at a single frequency, and the other one is a radar that detects the body motion by measuring the time shifts of sequential pulses.An intermediate solution thatjoins the advantages ofboth and overcomes their drawbacks is proposed. Through the use of a frequency sweep, in fact, it is possible to retrieve the equivalent information that UWB pulses are able to give, yet keeping the same contained hardware complexity of a CW system. At the same time, the proposed system proves to be robust and insensible to environmental changes. The theoretical studies have aimed at the demonstration that the solution under study helps in avoiding the blind frequencies that affect CW systems, because of sensitivity issues that depend on the variability of the reflection coefficient from the frequency and, as proved, from the harmonic content of the monitored motion. Supported by such theoretical studies, the preliminary tests are performed using laboratory instrumentation (a VNA and a commercial double ridge antenna) for a thorough campaign of measurements on assorted frequency bands, both in a controlled environment (anechoic angle) and in a concrete house, that inherently clutter the received signal. The second step involves the design and realization of a custom antenna, to be used in place of the double ridge and operating in a narrower band, which has demonstrated the same reliability of the commercial one. It has been verified in different conditions that the proposed system is able to detect both the position of the subject (i.e. distance from the antenna) and his breathing frequency, without any need for collaboration from the subject under measure. The final activity is the realization of a prototype of the device that implements the algorithms that have been studied. It is worth to highlight that the proposed system can be profitably adopted for Ambient Assisted Living framework, since it is not invasive and does not infringe the privacy of the end user, and yet it provides many valuable information about the subject's health status.
The aim of this paper is to present the main results of HDOMO, an Ambient Assisted Living (AAL) p... more The aim of this paper is to present the main results of HDOMO, an Ambient Assisted Living (AAL) project that involved 16 Small and Medium Enterprises (SMEs) and 2 research institutes. The objective of the project was to create an autonomous and automated domestic environment, primarily for elderly people and people with physical and motor disabilities. A known and familiar environment should help users in their daily activities and it should act as a virtual caregiver by calling, if necessary, relief efforts. Substantially, the aim of the project is to simplify the life of people in need of support, while keeping them autonomous in their private environment. From a technical point of view, the project provides the use of different Smart Objects (SOs), able to communicate among each other, in a cloud base infrastructure, and with the assisted users and their caregivers, in a perspective of interoperability and standardization of devices, usability and effectiveness of alarm systems. ...
Computer methods in biomechanics and biomedical engineering, 2017
In dentistry possible inflammatory episodes of oral cavity can be very frequent (periodontitis, m... more In dentistry possible inflammatory episodes of oral cavity can be very frequent (periodontitis, mucositis, peri-implantitis) and they can have serious consequences. Indeed, peri-implantitis is still the principal cause of implant failure. Impedance values of biological tissues are related to the physiological/pathological state of the tissue itself. In fact, an inflamed site exhibits an impedance value lower than that of the corresponding healthy tissue. Based on these observations, the aim of this work is to determine if impedancemetric measurements are able to provide information about the inflammatory state of tissues. A numerical 3D model has been realized to simulate the measurement conditions present in the event of inflammation around a dental implant. The aim is to understand if it is possible to determine the presence of an inflamed tissue and to locate its site, so that the treatment could be specifically focused in that specific area. A simplified geometry reproducing the...
ABSTRACT The aim of this paper is to investigate the capabilities of a novel electromagnetic tech... more ABSTRACT The aim of this paper is to investigate the capabilities of a novel electromagnetic technique designed for contactless monitoring of breathing activity in Ambient Assisted Living applications. The method is based on the transmission of a frequency sweep and the measurement of the reflection coefficient to determine the respiration rate of a subject. To date, the method is under optimization, but it has already shown interesting capabilities of calculating not only the respiration rate, but also additional features, as the position of the subject inside a room and his/her movements. After a brief mathematical description of the algorithm, some preliminary tests will be described concerning the monitoring of a human target inside a room. These first results clearly show the capability of the method to detect the subject, his breathing rate, position and physical activity. Of course further signal processing is required in order to distinguish between different types of movements and to classify them.
2011 IEEE International Symposium on Medical Measurements and Applications, 2011
The aim of this paper is to present a novel measurement method for the detection of the respirato... more The aim of this paper is to present a novel measurement method for the detection of the respiratory activity (respiration rate and respiration period) based on the use of a continuous wave (6 GHz) microwave radar reflectometry technique. The paper aims, in particular, to explore the effect on the signal quality of distance D between the sensing apparatus and the patient. The measurement method proposed is based on the measurement of the phase variation of the reflection coefficient (S 11) signal measured by a vectorial network analyzer connected to a double ridge horn antenna. The S 11 signal has been compared with the synchronous acquisition made by means of a laser Doppler vibrometer (LDVi), measuring the thorax oscillations caused by the respiratory activity. Both signals have been filtered in order to eliminate the effect of high frequency disturbances (heartbeat) and noise. Results show an high correlation between respiration peaks measured with the proposed system and with LDVi; a reduction of the amplitude of the S 11 signal phase (as well as the SNR) is reported in correspondence to an increasing of the distance D (-0.11 dB/cm). Tests have been repeated for standing as well as for sitting condition of the subject confirming a better signal quality for the later. Despite the fact that S 11 phase variation and SNR are reduced by the distance D, in our experiments, it is still possible to correctly measure the respiration period up to 2.5 m. Data measured show that the reflectometeric approach can be used to monitor at distance with sufficient high SNR (18 dB at 2.5 m) the respiration activity of a subject without the need of a direct contact with the subject skin by means of electrods of sensing belts.
2009 20th International Zurich Symposium on Electromagnetic Compatibility, 2009
The paper exhibits an array design for the source stirring technique in reverberation chambers. T... more The paper exhibits an array design for the source stirring technique in reverberation chambers. The development is pursued in two steps devoted to achieve a configuration of antennas that, fed by an electronic switching network, are able to provide the required statistics. In particular, the last step investigates the possibility to feed two antennas simultaneously.
Vision impairment is a physical and sensory disability affecting a large number of subjects aroun... more Vision impairment is a physical and sensory disability affecting a large number of subjects around the world. A large part of this subjects is aged 65 or older and their number grows faster than the overall population. In this work, a innovative sensing method, proposed by the research group of the Universita Politecnica delle Marche based on EM pulses, is presented together with some experimental results achieved in obstacles detection. The proposed approach accomplishes most of the operative requirements of electronic travel aids for visually impaired subjects and can provide additional information (height form the ground, distance and position of the obstacle) on obstacles respect to the available assistive technologies currently used by subjects affected by visual impairments.
ABSTRACT The safety area around the applicator of a high current pulse generator, able to magneti... more ABSTRACT The safety area around the applicator of a high current pulse generator, able to magnetically stimulate the human heart, is characterized in terms of allowable induced current. The magnetic field produced by the adopted coil is computed using a complete analytical model to determine the limit area allowed for medical operators. The International Commission on Non-Ionizing Radiation Protection recommendation is adopted for the occupational exposure limits. The presence of a ferrite tile close to the stimulation coil is also investigated. The ferrite tile enhances the field level on the patient side, making the magnetic stimulation more efficient. Experimental validation demonstrates the model's reliability.
IEEE Transactions on Instrumentation and Measurement, 2008
This paper presents two test benches for the characterization of a plasma column used as a radiat... more This paper presents two test benches for the characterization of a plasma column used as a radiating element. In particular, the main parameters to be quantified are the efficiency of the plasma antenna, the turn-on time of the column, and the conductivity of the plasma. The first two parameters are evaluated by measuring the field radiated by the plasma antenna compared with that of an equivalent copper antenna. For the conductivity, a reflectometric technique is used, wherein the plasma column is inserted inside a waveguide. The accuracy of the method is limited by the ill-conditioned relationship between the reflection coefficient and the plasma conductivity; nevertheless, it is sufficient to subdivide the range of the conductivity values into three regions (i.e., low, medium, and high conductivities) to determine the best operating conditions of the antenna.
IEEE Transactions on Electromagnetic Compatibility, 2008
A rigorous analysis of a dipole inside a resonant cavity with wall losses is carried out by solvi... more A rigorous analysis of a dipole inside a resonant cavity with wall losses is carried out by solving an electric field integral equation for the current along the antenna. Classic mode expansion is adopted to represent the cavity field, and method of moments is used to achieve the numerical solution of the problem, allowing us to describe the behavior of the antenna parameters in a resonant environment. The theoretical formulation of the problem is applied and validated for a realistic experimental situation, which typically occurs in shielding effectiveness measurements. The analysis focuses on the antenna factor (AF) in order to provide an estimation of the error that is committed when a free-space AF is used for field measurements in resonant structures. Index Terms-Antenna factor (AF), electric field integral equation (EFIE), method of moments (MoM), resonant cavity.
IEEE Transactions on Electromagnetic Compatibility, 2005
The paper investigates the possibility of reverberating a shielded room by means of source mode s... more The paper investigates the possibility of reverberating a shielded room by means of source mode stirring. The transmitting antenna position and orientation are randomly changed inside a sub-volume of the chamber. In general, antenna displacement can be achieved by a proper design of an array of antennas, where one or more antennas are activated at different time instants. This technique eliminates mechanical rotating paddles inside the chamber, and offers the advantage of a continuous wave (CW) operation with respect to the frequency stirring method. The preliminary experimental and simulated results encourage further investigation of the proposed technique.
IEEE Transactions on Electromagnetic Compatibility, 2009
A novel theoretical feasibility study to reverberate a large metallic chamber is proposed. The me... more A novel theoretical feasibility study to reverberate a large metallic chamber is proposed. The method is based on the displacement of a radiating antenna inside the chamber, and the reverberating effect is obtained by coupling the antenna current in different ways with the cavity modes. This technique eliminates mechanical rotating paddles inside the chamber and offers the advantage of a continuous-wave operation compared with the frequency stirring method. The reverberating characteristics of the proposed technique are evaluated by calculating the field statistics. The analyzed situation concerns a real antenna, and its radiation into the reverberation chamber is modeled using Green's function of cavity. The numerical problem is solved by the method of moment. The model has been tested and is able to rigorously characterize the reverberating environment for the design and optimization of antenna configurations to be addressed in future studies.
IEEE Transactions on Electromagnetic Compatibility, 2003
The use of current probes for the injection of wide-band disturbance in electromagnetic compatibi... more The use of current probes for the injection of wide-band disturbance in electromagnetic compatibility applications requires their accurate characterization up to few gigahertz. While the representation of the current probe with a simple transformer is acceptable at low frequencies, the spectral content of fast signals requires models which are accurate even at gigahertz frequencies. This can be accomplished directly by measurements in the frequency domain (FD), making use of a-matrix representation of the probe, or in the time domain (TD), recovering the transfer functions from the impulse responses measurement. Both techniques suffer limitations due to numerical and experimental problems; in particular, the FD approach leads to the solution of an inverse problem, with numerical instabilities in the high-frequency range, whereas the TD approach is not so accurate in the low-frequency range of the sought transfer function. The paper combines the two techniques to overcome these difficulties and achieve a better accuracy across the overall bandwidth. The characterization of a commercially available current probe allows comparison of numerical results with experimental measurements. Index Terms-Bulk current injection (BCI), current probe, time domain (TD).
IEEE Transactions on Antennas and Propagation, 2011
Plasma can be used to create antennas: its conduc- tivity is given by free electrons resulting fr... more Plasma can be used to create antennas: its conduc- tivity is given by free electrons resulting from gas ionization. This process is obtained with the application of an intense electromag- netic field to a glass tube filled with a low pressure gas. The pump signal needed for ionization and gas discharge parameters have to becarefullychoseninordertooptimizeplasmaantennadesignand realization; in particular discharge working conditions have to be defined to obtain the desired antenna properties in terms of effi- ciency and effective length. For this purpose a self-consistent nu- merical model of a surface wave driven plasma column has been developed. This tool helps to understand the physical aspects in- volved in the problem and allows a parametric investigation to be carried out. Index Terms—Antenna, FDTD, plasma, surface waves.
IEEE Transactions on Antennas and Propagation, 2006
AbstractThe design procedure for a switching beam antenna for wireless communication systems is ... more AbstractThe design procedure for a switching beam antenna for wireless communication systems is given. The antenna can ro-tate the beam over the whole azimuthal angle exploiting its geomet-rical and electrical cylindrical symmetry. The required directivity and the beam ...
IEEE Transactions on Antennas and Propagation, 2011
ABSTRACT The possibility of using a surfaguide device as plasma source for plasma antenna applica... more ABSTRACT The possibility of using a surfaguide device as plasma source for plasma antenna application has been experimentally investigated. The surfaguide was optimized, realized and used for the ignition of a plasma column to be used as a radiating structure: the coupling with the radiated signal network and plasma antenna efficiency were measured showing that a surfaguide can be effectively used to create and sustain the plasma conductive medium. A plasma diagnostic technique was also developed to evaluate the plasma column length and plasma conductivity with respect to the power supplied. These measurements highlighted that plasma antenna properties are strongly affected by the pump signal and therefore this signal has to be optimized in order to have the highest conductivity.
The feasibility of a plasma antenna is given by plasma conductivity: this is the key parameter th... more The feasibility of a plasma antenna is given by plasma conductivity: this is the key parameter that has to be determined and optimized to characterize the radiation properties of such antennas. This paper presents a self-consistent model for the characterization of ...
Human Monitoring, Smart Health and Assisted Living: Techniques and technologies, 2017
Respiratory rate is a vital parameter of primary importance in medicine, sport/fitness and wellne... more Respiratory rate is a vital parameter of primary importance in medicine, sport/fitness and wellness in general, especially for most vulnerable categories of people like children and elderly people. Contactless determination of breathing activity provides a powerful and essential mean for evaluating this parameter in subjects who cannot accommodate physical sensors on their bodies. In hospital such subjects may be intensive care patients, prematurely born children and hosts of burn units. Moreover, also for long-term measurements of healthy people, for example, an elder living in home alone or in a care centre, invasive systems prove to be uncomfortable and annoying. Even for a night-time diagnosis of respiratory sleep disorders, like apnoea and hypopnoea, they demonstrate to interfere with the sleep regularity. Therefore, in the last decades many electronic devices have been conceived and realized to detect such an important parameter along with different branches of physics: strain gauges, ultrasounds, optics, thermometry, etc. This chapter presents the theoretical studies, the design and realization of a standalone Electromagnetic (EM) system for contactless determination of breathing frequency and subject's activity. Two major EM solutions are already known in the literature, continuous wave (CW) systems, and ultra-wideband (UWB) systems. The first evaluates the Doppler effect caused by the chest displacement during breathing at a single frequency, and the other one is a radar that detects the body motion by measuring the time shifts of sequential pulses.An intermediate solution thatjoins the advantages ofboth and overcomes their drawbacks is proposed. Through the use of a frequency sweep, in fact, it is possible to retrieve the equivalent information that UWB pulses are able to give, yet keeping the same contained hardware complexity of a CW system. At the same time, the proposed system proves to be robust and insensible to environmental changes. The theoretical studies have aimed at the demonstration that the solution under study helps in avoiding the blind frequencies that affect CW systems, because of sensitivity issues that depend on the variability of the reflection coefficient from the frequency and, as proved, from the harmonic content of the monitored motion. Supported by such theoretical studies, the preliminary tests are performed using laboratory instrumentation (a VNA and a commercial double ridge antenna) for a thorough campaign of measurements on assorted frequency bands, both in a controlled environment (anechoic angle) and in a concrete house, that inherently clutter the received signal. The second step involves the design and realization of a custom antenna, to be used in place of the double ridge and operating in a narrower band, which has demonstrated the same reliability of the commercial one. It has been verified in different conditions that the proposed system is able to detect both the position of the subject (i.e. distance from the antenna) and his breathing frequency, without any need for collaboration from the subject under measure. The final activity is the realization of a prototype of the device that implements the algorithms that have been studied. It is worth to highlight that the proposed system can be profitably adopted for Ambient Assisted Living framework, since it is not invasive and does not infringe the privacy of the end user, and yet it provides many valuable information about the subject's health status.
The aim of this paper is to present the main results of HDOMO, an Ambient Assisted Living (AAL) p... more The aim of this paper is to present the main results of HDOMO, an Ambient Assisted Living (AAL) project that involved 16 Small and Medium Enterprises (SMEs) and 2 research institutes. The objective of the project was to create an autonomous and automated domestic environment, primarily for elderly people and people with physical and motor disabilities. A known and familiar environment should help users in their daily activities and it should act as a virtual caregiver by calling, if necessary, relief efforts. Substantially, the aim of the project is to simplify the life of people in need of support, while keeping them autonomous in their private environment. From a technical point of view, the project provides the use of different Smart Objects (SOs), able to communicate among each other, in a cloud base infrastructure, and with the assisted users and their caregivers, in a perspective of interoperability and standardization of devices, usability and effectiveness of alarm systems. ...
Computer methods in biomechanics and biomedical engineering, 2017
In dentistry possible inflammatory episodes of oral cavity can be very frequent (periodontitis, m... more In dentistry possible inflammatory episodes of oral cavity can be very frequent (periodontitis, mucositis, peri-implantitis) and they can have serious consequences. Indeed, peri-implantitis is still the principal cause of implant failure. Impedance values of biological tissues are related to the physiological/pathological state of the tissue itself. In fact, an inflamed site exhibits an impedance value lower than that of the corresponding healthy tissue. Based on these observations, the aim of this work is to determine if impedancemetric measurements are able to provide information about the inflammatory state of tissues. A numerical 3D model has been realized to simulate the measurement conditions present in the event of inflammation around a dental implant. The aim is to understand if it is possible to determine the presence of an inflamed tissue and to locate its site, so that the treatment could be specifically focused in that specific area. A simplified geometry reproducing the...
ABSTRACT The aim of this paper is to investigate the capabilities of a novel electromagnetic tech... more ABSTRACT The aim of this paper is to investigate the capabilities of a novel electromagnetic technique designed for contactless monitoring of breathing activity in Ambient Assisted Living applications. The method is based on the transmission of a frequency sweep and the measurement of the reflection coefficient to determine the respiration rate of a subject. To date, the method is under optimization, but it has already shown interesting capabilities of calculating not only the respiration rate, but also additional features, as the position of the subject inside a room and his/her movements. After a brief mathematical description of the algorithm, some preliminary tests will be described concerning the monitoring of a human target inside a room. These first results clearly show the capability of the method to detect the subject, his breathing rate, position and physical activity. Of course further signal processing is required in order to distinguish between different types of movements and to classify them.
2011 IEEE International Symposium on Medical Measurements and Applications, 2011
The aim of this paper is to present a novel measurement method for the detection of the respirato... more The aim of this paper is to present a novel measurement method for the detection of the respiratory activity (respiration rate and respiration period) based on the use of a continuous wave (6 GHz) microwave radar reflectometry technique. The paper aims, in particular, to explore the effect on the signal quality of distance D between the sensing apparatus and the patient. The measurement method proposed is based on the measurement of the phase variation of the reflection coefficient (S 11) signal measured by a vectorial network analyzer connected to a double ridge horn antenna. The S 11 signal has been compared with the synchronous acquisition made by means of a laser Doppler vibrometer (LDVi), measuring the thorax oscillations caused by the respiratory activity. Both signals have been filtered in order to eliminate the effect of high frequency disturbances (heartbeat) and noise. Results show an high correlation between respiration peaks measured with the proposed system and with LDVi; a reduction of the amplitude of the S 11 signal phase (as well as the SNR) is reported in correspondence to an increasing of the distance D (-0.11 dB/cm). Tests have been repeated for standing as well as for sitting condition of the subject confirming a better signal quality for the later. Despite the fact that S 11 phase variation and SNR are reduced by the distance D, in our experiments, it is still possible to correctly measure the respiration period up to 2.5 m. Data measured show that the reflectometeric approach can be used to monitor at distance with sufficient high SNR (18 dB at 2.5 m) the respiration activity of a subject without the need of a direct contact with the subject skin by means of electrods of sensing belts.
2009 20th International Zurich Symposium on Electromagnetic Compatibility, 2009
The paper exhibits an array design for the source stirring technique in reverberation chambers. T... more The paper exhibits an array design for the source stirring technique in reverberation chambers. The development is pursued in two steps devoted to achieve a configuration of antennas that, fed by an electronic switching network, are able to provide the required statistics. In particular, the last step investigates the possibility to feed two antennas simultaneously.
Vision impairment is a physical and sensory disability affecting a large number of subjects aroun... more Vision impairment is a physical and sensory disability affecting a large number of subjects around the world. A large part of this subjects is aged 65 or older and their number grows faster than the overall population. In this work, a innovative sensing method, proposed by the research group of the Universita Politecnica delle Marche based on EM pulses, is presented together with some experimental results achieved in obstacles detection. The proposed approach accomplishes most of the operative requirements of electronic travel aids for visually impaired subjects and can provide additional information (height form the ground, distance and position of the obstacle) on obstacles respect to the available assistive technologies currently used by subjects affected by visual impairments.
ABSTRACT The safety area around the applicator of a high current pulse generator, able to magneti... more ABSTRACT The safety area around the applicator of a high current pulse generator, able to magnetically stimulate the human heart, is characterized in terms of allowable induced current. The magnetic field produced by the adopted coil is computed using a complete analytical model to determine the limit area allowed for medical operators. The International Commission on Non-Ionizing Radiation Protection recommendation is adopted for the occupational exposure limits. The presence of a ferrite tile close to the stimulation coil is also investigated. The ferrite tile enhances the field level on the patient side, making the magnetic stimulation more efficient. Experimental validation demonstrates the model's reliability.
IEEE Transactions on Instrumentation and Measurement, 2008
This paper presents two test benches for the characterization of a plasma column used as a radiat... more This paper presents two test benches for the characterization of a plasma column used as a radiating element. In particular, the main parameters to be quantified are the efficiency of the plasma antenna, the turn-on time of the column, and the conductivity of the plasma. The first two parameters are evaluated by measuring the field radiated by the plasma antenna compared with that of an equivalent copper antenna. For the conductivity, a reflectometric technique is used, wherein the plasma column is inserted inside a waveguide. The accuracy of the method is limited by the ill-conditioned relationship between the reflection coefficient and the plasma conductivity; nevertheless, it is sufficient to subdivide the range of the conductivity values into three regions (i.e., low, medium, and high conductivities) to determine the best operating conditions of the antenna.
IEEE Transactions on Electromagnetic Compatibility, 2008
A rigorous analysis of a dipole inside a resonant cavity with wall losses is carried out by solvi... more A rigorous analysis of a dipole inside a resonant cavity with wall losses is carried out by solving an electric field integral equation for the current along the antenna. Classic mode expansion is adopted to represent the cavity field, and method of moments is used to achieve the numerical solution of the problem, allowing us to describe the behavior of the antenna parameters in a resonant environment. The theoretical formulation of the problem is applied and validated for a realistic experimental situation, which typically occurs in shielding effectiveness measurements. The analysis focuses on the antenna factor (AF) in order to provide an estimation of the error that is committed when a free-space AF is used for field measurements in resonant structures. Index Terms-Antenna factor (AF), electric field integral equation (EFIE), method of moments (MoM), resonant cavity.
IEEE Transactions on Electromagnetic Compatibility, 2005
The paper investigates the possibility of reverberating a shielded room by means of source mode s... more The paper investigates the possibility of reverberating a shielded room by means of source mode stirring. The transmitting antenna position and orientation are randomly changed inside a sub-volume of the chamber. In general, antenna displacement can be achieved by a proper design of an array of antennas, where one or more antennas are activated at different time instants. This technique eliminates mechanical rotating paddles inside the chamber, and offers the advantage of a continuous wave (CW) operation with respect to the frequency stirring method. The preliminary experimental and simulated results encourage further investigation of the proposed technique.
IEEE Transactions on Electromagnetic Compatibility, 2009
A novel theoretical feasibility study to reverberate a large metallic chamber is proposed. The me... more A novel theoretical feasibility study to reverberate a large metallic chamber is proposed. The method is based on the displacement of a radiating antenna inside the chamber, and the reverberating effect is obtained by coupling the antenna current in different ways with the cavity modes. This technique eliminates mechanical rotating paddles inside the chamber and offers the advantage of a continuous-wave operation compared with the frequency stirring method. The reverberating characteristics of the proposed technique are evaluated by calculating the field statistics. The analyzed situation concerns a real antenna, and its radiation into the reverberation chamber is modeled using Green's function of cavity. The numerical problem is solved by the method of moment. The model has been tested and is able to rigorously characterize the reverberating environment for the design and optimization of antenna configurations to be addressed in future studies.
IEEE Transactions on Electromagnetic Compatibility, 2003
The use of current probes for the injection of wide-band disturbance in electromagnetic compatibi... more The use of current probes for the injection of wide-band disturbance in electromagnetic compatibility applications requires their accurate characterization up to few gigahertz. While the representation of the current probe with a simple transformer is acceptable at low frequencies, the spectral content of fast signals requires models which are accurate even at gigahertz frequencies. This can be accomplished directly by measurements in the frequency domain (FD), making use of a-matrix representation of the probe, or in the time domain (TD), recovering the transfer functions from the impulse responses measurement. Both techniques suffer limitations due to numerical and experimental problems; in particular, the FD approach leads to the solution of an inverse problem, with numerical instabilities in the high-frequency range, whereas the TD approach is not so accurate in the low-frequency range of the sought transfer function. The paper combines the two techniques to overcome these difficulties and achieve a better accuracy across the overall bandwidth. The characterization of a commercially available current probe allows comparison of numerical results with experimental measurements. Index Terms-Bulk current injection (BCI), current probe, time domain (TD).
IEEE Transactions on Antennas and Propagation, 2011
Plasma can be used to create antennas: its conduc- tivity is given by free electrons resulting fr... more Plasma can be used to create antennas: its conduc- tivity is given by free electrons resulting from gas ionization. This process is obtained with the application of an intense electromag- netic field to a glass tube filled with a low pressure gas. The pump signal needed for ionization and gas discharge parameters have to becarefullychoseninordertooptimizeplasmaantennadesignand realization; in particular discharge working conditions have to be defined to obtain the desired antenna properties in terms of effi- ciency and effective length. For this purpose a self-consistent nu- merical model of a surface wave driven plasma column has been developed. This tool helps to understand the physical aspects in- volved in the problem and allows a parametric investigation to be carried out. Index Terms—Antenna, FDTD, plasma, surface waves.
IEEE Transactions on Antennas and Propagation, 2006
AbstractThe design procedure for a switching beam antenna for wireless communication systems is ... more AbstractThe design procedure for a switching beam antenna for wireless communication systems is given. The antenna can ro-tate the beam over the whole azimuthal angle exploiting its geomet-rical and electrical cylindrical symmetry. The required directivity and the beam ...
IEEE Transactions on Antennas and Propagation, 2011
ABSTRACT The possibility of using a surfaguide device as plasma source for plasma antenna applica... more ABSTRACT The possibility of using a surfaguide device as plasma source for plasma antenna application has been experimentally investigated. The surfaguide was optimized, realized and used for the ignition of a plasma column to be used as a radiating structure: the coupling with the radiated signal network and plasma antenna efficiency were measured showing that a surfaguide can be effectively used to create and sustain the plasma conductive medium. A plasma diagnostic technique was also developed to evaluate the plasma column length and plasma conductivity with respect to the power supplied. These measurements highlighted that plasma antenna properties are strongly affected by the pump signal and therefore this signal has to be optimized in order to have the highest conductivity.
The feasibility of a plasma antenna is given by plasma conductivity: this is the key parameter th... more The feasibility of a plasma antenna is given by plasma conductivity: this is the key parameter that has to be determined and optimized to characterize the radiation properties of such antennas. This paper presents a self-consistent model for the characterization of ...
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