Pub Date : 2021-04-08DOI: 10.36227/TECHRXIV.14346179.V1
S. Zeising, D. Anzai, A. Thalmayer, Georg Fischer, J. Kirchner
Wireless capsule endoscopy is an established medical application for the examination of the gastrointestinal tract. However, the robust and precise localization of these capsules is still in need of further scientific investigation. This paper presents an innovative differential magnetic localization method for capsule endoscopy to prevent interference caused by the geomagnetic field. The effect of changing the orientation of the capsule on the localization process was also examined. Simulations using COMSOL Multiphysics with the superimposed geomagnetic field were performed. The Levenberg–Marquardt algorithm was applied in MATLAB to estimate the position and orientation of the capsule. Comparing the proposed differential method with the absolute magnetic localization method under ideal conditions, the mean position and orientation errors were reduced by three orders in magnitude to less than 0.1 mm and 0.1 ° respectively. Even if sensor non-idealities are considered, the simulationbased results reveal that our proposed method is competitive with state-of-the-art geomagnetic compensation methods for static magnetic localization of capsule endoscopes.The achieved localization accuracy by applying the differential method is not dependent on the rotation of the localization system relative to the geomagnetic flux density under the made assumptions and the impact of the magnet orientation is neglectable. It is concluded that the proposed method is capable of preventing all interference whose components are approximately equal at all sensors with identical orientation.
{"title":"Innovative Differential Magnetic Localization Method for Capsule Endoscopy to Prevent Interference Caused by the Geomagnetic Field","authors":"S. Zeising, D. Anzai, A. Thalmayer, Georg Fischer, J. Kirchner","doi":"10.36227/TECHRXIV.14346179.V1","DOIUrl":"https://doi.org/10.36227/TECHRXIV.14346179.V1","url":null,"abstract":"Wireless capsule endoscopy is an established medical application for the examination of the gastrointestinal tract. However, the robust and precise localization of these capsules is still in need of further scientific investigation. This paper presents an innovative differential magnetic localization method for capsule endoscopy to prevent interference caused by the geomagnetic field. The effect of changing the orientation of the capsule on the localization process was also examined. Simulations using COMSOL Multiphysics with the superimposed geomagnetic field were performed. The Levenberg–Marquardt algorithm was applied in MATLAB to estimate the position and orientation of the capsule. Comparing the proposed differential method with the absolute magnetic localization method under ideal conditions, the mean position and orientation errors were reduced by three orders in magnitude to less than 0.1 mm and 0.1 ° respectively. Even if sensor non-idealities are considered, the simulationbased results reveal that our proposed method is competitive with state-of-the-art geomagnetic compensation methods for static magnetic localization of capsule endoscopes.The achieved localization accuracy by applying the differential method is not dependent on the rotation of the localization system relative to the geomagnetic flux density under the made assumptions and the impact of the magnet orientation is neglectable. It is concluded that the proposed method is capable of preventing all interference whose components are approximately equal at all sensors with identical orientation. \u0000","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48222988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-03DOI: 10.5194/EGUSPHERE-EGU21-3163
C. Jacobi, F. Lilienthal, D. Korotyshkin, E. Merzlyakov, G. Stober
Observations of upper mesosphere/lower thermosphere (MLT) wind have been performed at Collm (51°N, 13°E) and Kazan (56°N, 49°E), using two SKiYMET all-sky meteor radars with similar configuration. Daily vertical profiles of mean winds and tidal amplitudes have been constructed from hourly horizontal winds. We analyze the response of mean winds and tidal amplitudes to geomagnetic disturbances. To this end we compare winds and amplitudes for very quiet (Ap ≤ 5) and unsettled/disturbed (Ap ≥ 20) geomagnetic conditions. Zonal winds in both the mesosphere and lower thermosphere are weaker during disturbed conditions for both summer and winter. The summer equatorward meridional wind jet is weaker for disturbed geomagnetic conditions. Tendencies over Collm and Kazan for geomagnetic effects on mean winds qualitatively agree during most of the year. For the diurnal tide, amplitudes in summer are smaller in the mesosphere but greater in the lower thermosphere, but no clear tendency is seen for winter. Semidiurnal tidal amplitudes increase during geomagnetic active days in summer and winter. Terdiurnal amplitudes are slightly reduced in the mesosphere during disturbed days, but no clear effect is visible for the lower thermosphere. Overall, while there is a noticeable effect of geomagnetic variability on the mean wind, the effect on tidal amplitudes, except for the semidiurnal tide, is relatively small and partly different over Collm and Kazan.
{"title":"Influence of geomagnetic disturbances on midlatitude mesosphere/lower thermosphere mean winds and tides ","authors":"C. Jacobi, F. Lilienthal, D. Korotyshkin, E. Merzlyakov, G. Stober","doi":"10.5194/EGUSPHERE-EGU21-3163","DOIUrl":"https://doi.org/10.5194/EGUSPHERE-EGU21-3163","url":null,"abstract":"<p>Observations of upper mesosphere/lower thermosphere (MLT) wind have been performed at Collm (51°N, 13°E) and Kazan (56°N, 49°E), using two SKiYMET all-sky meteor radars with similar configuration. Daily vertical profiles of mean winds and tidal amplitudes have been constructed from hourly horizontal winds. We analyze the response of mean winds and tidal amplitudes to geomagnetic disturbances. To this end we compare winds and amplitudes for very quiet (Ap ≤ 5) and unsettled/disturbed (Ap ≥ 20) geomagnetic conditions. Zonal winds in both the mesosphere and lower thermosphere are weaker during disturbed conditions for both summer and winter. The summer equatorward meridional wind jet is weaker for disturbed geomagnetic conditions. Tendencies over Collm and Kazan for geomagnetic effects on mean winds qualitatively agree during most of the year. For the diurnal tide, amplitudes in summer are smaller in the mesosphere but greater in the lower thermosphere, but no clear tendency is seen for winter. Semidiurnal tidal amplitudes increase during geomagnetic active days in summer and winter. Terdiurnal amplitudes are slightly reduced in the mesosphere during disturbed days, but no clear effect is visible for the lower thermosphere. Overall, while there is a noticeable effect of geomagnetic variability on the mean wind, the effect on tidal amplitudes, except for the semidiurnal tide, is relatively small and partly different over Collm and Kazan.</p>","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48108655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Analog computers can be revived as a feasible technology platform for low precision, energy efficient and fast computing. We justify this statement by measuring the performance of a modern analog computer and comparing it with that of traditional digital processors. General statements are made about the solution of ordinary and partial differential equations. Computational fluid dynamics are discussed as an example of large scale scientific computing applications. Several models are proposed which demonstrate the benefits of analog and digital-analog hybrid computing.
{"title":"Using analog computers in today's largest computational challenges","authors":"Sven Köppel, B. Ulmann, Lars Heimann, D. Killat","doi":"10.5194/ars-19-105-2021","DOIUrl":"https://doi.org/10.5194/ars-19-105-2021","url":null,"abstract":"Abstract. Analog computers can be revived as a feasible technology platform for low\u0000precision, energy efficient and fast computing. We justify this statement by\u0000measuring the performance of a modern analog computer and comparing it with\u0000that of traditional digital processors. General statements are made about the solution\u0000of ordinary and partial differential equations.\u0000Computational fluid dynamics are discussed as an example of large scale scientific\u0000computing applications. Several models are proposed which demonstrate the benefits\u0000of analog and digital-analog hybrid computing.\u0000","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2021-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42715279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Near-field measurements are commonly performed in anechoic chambers which limits the flexibility of the measurements and requires high precision equipment to achieve exact results. In this contribution, we investigate a simple near-field measurement setup which does not use any sophisticated positioning system nor operates in a controlled environment. Instead, the probe antenna is moved by an operator person while the probe position is measured by a laser tracker. This implies that the measurement results will have a higher error level in comparison with antenna chamber measurements. However, excellent error levels are not always necessary, especially when it comes to on-site testing of the principle functionality of antennas. Measurement results are shown to illustrate the performance of the system.
{"title":"Near-Field Antenna Measurements with Manual Collection of the Measurement Samples","authors":"F. Faul, H. Steiner, T. Eibert","doi":"10.5194/ars-18-17-2020","DOIUrl":"https://doi.org/10.5194/ars-18-17-2020","url":null,"abstract":"Near-field measurements are commonly performed in anechoic chambers which limits the flexibility of the measurements and requires high precision equipment to achieve exact results. In this contribution, we investigate a simple near-field measurement setup which does not use any sophisticated positioning system nor operates in a controlled environment. Instead, the probe antenna is moved by an operator person while the probe position is measured by a laser tracker. This implies that the measurement results will have a higher error level in comparison with antenna chamber measurements. However, excellent error levels are not always necessary, especially when it comes to on-site testing of the principle functionality of antennas. Measurement results are shown to illustrate the performance of the system.","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":"18 1","pages":"17-22"},"PeriodicalIF":0.4,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46659398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. When a disaster strikes, response teams can nowadays rely on recent advances in technology. This approach improves the definition of a disaster management strategy. The use of autonomous systems during rescue operations allows, for example, to reach places that may be inaccessible or dangerous to human rescuers. In this context, both the design and the configuration of an autonomous system, including its embedded instruments (e.g. sensors), play a very important role in the overall outcome of the rescue mission. An incorrect configuration can lead to the acquisition of inaccurate or erroneous data and may result in incorrect information provided to rescuers. How can we ensure that the configuration of the autonomous systems is correct for a target mission? We propose to validate this configuration by testing the behaviour of the autonomous systems and their equipment in a virtual environment. To do this, system, sensors, space environment (geometry, etc.), prevailing conditions at the intervention site (weather, etc.) and mission scenario must be modelled in a 3D simulation system. The results of these simulations allow to apply in real time the modifications required to better adapt the configuration to the objectives of the mission. These simulations must be performed prior to the deployment of rescue teams to speed the development of a rescue management strategy. In this contribution, we propose a protocol to enhance an existing simulation environment to make it adapt to support disaster management. Then, we validate it through a case study in which we show the approach to correctly configure a LIDAR for a realistic mission. Such simulations allowed us to quantitatively configure the parameters of the LIDAR mounted on an existing disaster management rover, in order to keep the energy consumption limited while guaranteeing a correct functioning of the system. Resuming, the expected results are: (i) the assessment of the suitability of system for the mission, (ii) the choice of the quantitative features which characterize such equipment, (iii) the expectation of mission success and (iv) the probability which the system survives and completes the mission.
{"title":"Towards 3D Simulation for Disaster Intervention Robot Behaviour Assessment","authors":"Matteo Bertolino, T. Tanzi","doi":"10.5194/ars-18-23-2020","DOIUrl":"https://doi.org/10.5194/ars-18-23-2020","url":null,"abstract":"Abstract. When a disaster strikes, response teams can nowadays rely on recent advances in technology. This approach improves the definition of a disaster management strategy. The use of autonomous systems during rescue operations allows, for example, to reach places that may be inaccessible or dangerous to human rescuers. In this context, both the design and the configuration of an autonomous system, including its embedded instruments (e.g. sensors), play a very important role in the overall outcome of the rescue mission. An incorrect configuration can lead to the acquisition of inaccurate or erroneous data and may result in incorrect information provided to rescuers. How can we ensure that the configuration of the autonomous systems is correct for a target mission? We propose to validate this configuration by testing the behaviour of the autonomous systems and their equipment in a virtual environment. To do this, system, sensors, space environment (geometry, etc.), prevailing conditions at the intervention site (weather, etc.) and mission scenario must be modelled in a 3D simulation system. The results of these simulations allow to apply in real time the modifications required to better adapt the configuration to the objectives of the mission. These simulations must be performed prior to the deployment of rescue teams to speed the development of a rescue management strategy. In this contribution, we propose a protocol to enhance an existing simulation environment to make it adapt to support disaster management. Then, we validate it through a case study in which we show the approach to correctly configure a LIDAR for a realistic mission. Such simulations allowed us to quantitatively configure the parameters of the LIDAR mounted on an existing disaster management rover, in order to keep the energy consumption limited while guaranteeing a correct functioning of the system. Resuming, the expected results are: (i) the assessment of the suitability of system for the mission, (ii) the choice of the quantitative features which characterize such equipment, (iii) the expectation of mission success and (iv) the probability which the system survives and completes the mission.","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":" ","pages":""},"PeriodicalIF":0.4,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48935616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The susceptibility of interference victims can significantly be influenced by the presence of nonlinear circuit elements. In addition to the well known occurrence of intermodulation-frequencies, other effects can be observed as well. Recently, a nonlinear energy storage effect has been discovered which is due to the presence of nonlinearly loaded loop antennas if excited by an HPEM-excitation. In this contribution, this effect is further studied by experiment. It is seen that the nonlinear energy storage effect can be reproduced by means of a rather simple experimental setup. This allows to straighforwardly study parameter variations in order to attain an improved understanding of the considered effect.
{"title":"Experimental Investigation of a Nonlinear Energy Storage Effect due to High Power Electromagnetic Excitation","authors":"R. Michels, M. Schaarschmidt, F. Gronwald","doi":"10.5194/ars-18-75-2020","DOIUrl":"https://doi.org/10.5194/ars-18-75-2020","url":null,"abstract":"The susceptibility of interference victims can significantly be influenced by the presence of nonlinear circuit elements. In addition to the well known occurrence of intermodulation-frequencies, other effects can be observed as well. Recently, a nonlinear energy storage effect has been discovered which is due to the presence of nonlinearly loaded loop antennas if excited by an HPEM-excitation. In this contribution, this effect is further studied by experiment. It is seen that the nonlinear energy storage effect can be reproduced by means of a rather simple experimental setup. This allows to straighforwardly study parameter variations in order to attain an improved understanding of the considered effect.","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":"18 1","pages":"75-82"},"PeriodicalIF":0.4,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45943155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We introduce a new tunable reflectarray element for an operation frequency of 26 GHz in the k-band. It is shown that a 340 continuous tunning range of the reflected wave can be accomplished by using an aperture-coupled patch antenna with only one single varactor diode. The simplified design and the small needed space make it usable for k-band reflectarrays with many elements. The functionality of the reflectarray element is explained and the crucial parts are analyzed. The approach to get a full phase shift is discussed in detail. A bias-T is developed to provide the control voltage to the varactor diode without interfering with the high frequency path. The high frequency path and the DCpath are decoupled by 39 dB using a bias-T. A commercial off-the-shelf varactor diode is selected and its functionality at 26 GHz is verified. Therefore, a test printed circuit board with through, reflect, line standards is developed to de-embed the varactor diode and to evaluate it with a vector network analyzer. The reflectarray is simulated in a unit cell with plane wave excitation and periodic boundary condition using the simulation software package CST Microwave StudioTM.
{"title":"Design of a continuously tunable reflectarray element for 5G metrology in the k-band","authors":"T. Harz, T. Kleine-Ostmann, T. Schrader","doi":"10.5194/ars-18-1-2020","DOIUrl":"https://doi.org/10.5194/ars-18-1-2020","url":null,"abstract":"We introduce a new tunable reflectarray element for an operation frequency of 26 GHz in the k-band. It is shown that a 340 continuous tunning range of the reflected wave can be accomplished by using an aperture-coupled patch antenna with only one single varactor diode. The simplified design and the small needed space make it usable for k-band reflectarrays with many elements. The functionality of the reflectarray element is explained and the crucial parts are analyzed. The approach to get a full phase shift is discussed in detail. A bias-T is developed to provide the control voltage to the varactor diode without interfering with the high frequency path. The high frequency path and the DCpath are decoupled by 39 dB using a bias-T. A commercial off-the-shelf varactor diode is selected and its functionality at 26 GHz is verified. Therefore, a test printed circuit board with through, reflect, line standards is developed to de-embed the varactor diode and to evaluate it with a vector network analyzer. The reflectarray is simulated in a unit cell with plane wave excitation and periodic boundary condition using the simulation software package CST Microwave StudioTM.","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":"18 1","pages":"1-5"},"PeriodicalIF":0.4,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48124489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sassan Schäfer, Simon Müller, Daniel Schmiech, A. Diewald
Radar systems for contactless vital sign monitoring are well known and an actual object of research. These radar-based sensors could be used for monitoring of elderly people in their homes but also for detecting the activity of prisoners and to control electrical devices (light, audio, etc.) in smart living environments. Mostly these sensors are foreseen to be mounted on the ceiling in the middle of a room. In retirement homes the rooms are mostly rectangular and of standardized size. Furniture like beds and seating are found at the borders or the corners of the room. As the propagation path from the center of the room ceiling to the borders and corners of a room is 1.4 and 1.7 time longer the power reflected by people located there is 6 or even 10 dB lower than if located in the center of the room. Furthermore classical antennas in microstrip technology are strengthening radiation in broadside direction. Radar systems with only one single planar antenna must be mounted horizontally aligned when measuring in all directions. Thus an antenna pattern which is increasing radiation in the room corners and borders for compensation of free space loss is needed. In this contribution a specification of classical room sizes in retirement homes are given. A method for shaping the antenna gain in the E-plane by an one-dimensional series-fed traveling wave patch array and in the H-plane by an antenna feeding network for improvement of people detection in the room borders and corners is presented for a 24 GHz digital beamforming (DBF) radar system. The feeding network is a parallel-fed power divider for microstrip patch antennas at 24 GHz. Both approaches are explained in theory. The design parameters and the layout of the antennas are given. The simulation of the antenna arrays are executed with CST MWS. Simulations and measurements of the proposed antennas are compared to each other. Both antennas are used for the transmit and the receive channel either. The sensor topology of the radar system is explained. Furthermore the measurement results of the protoype are presented and discussed.
{"title":"Radar system with dedicated planar traveling wave antennas for elderly people monitoring","authors":"Sassan Schäfer, Simon Müller, Daniel Schmiech, A. Diewald","doi":"10.5194/ars-18-97-2020","DOIUrl":"https://doi.org/10.5194/ars-18-97-2020","url":null,"abstract":"Radar systems for contactless vital sign monitoring are well known and an actual object of research. These radar-based sensors could be used for monitoring of elderly people in their homes but also for detecting the activity of prisoners and to control electrical devices (light, audio, etc.) in smart living environments. Mostly these sensors are foreseen to be mounted on the ceiling in the middle of a room. In retirement homes the rooms are mostly rectangular and of standardized size. Furniture like beds and seating are found at the borders or the corners of the room. As the propagation path from the center of the room ceiling to the borders and corners of a room is 1.4 and 1.7 time longer the power reflected by people located there is 6 or even 10 dB lower than if located in the center of the room. Furthermore classical antennas in microstrip technology are strengthening radiation in broadside direction. Radar systems with only one single planar antenna must be mounted horizontally aligned when measuring in all directions. Thus an antenna pattern which is increasing radiation in the room corners and borders for compensation of free space loss is needed. In this contribution a specification of classical room sizes in retirement homes are given. A method for shaping the antenna gain in the E-plane by an one-dimensional series-fed traveling wave patch array and in the H-plane by an antenna feeding network for improvement of people detection in the room borders and corners is presented for a 24 GHz digital beamforming (DBF) radar system. The feeding network is a parallel-fed power divider for microstrip patch antennas at 24 GHz. Both approaches are explained in theory. The design parameters and the layout of the antennas are given. The simulation of the antenna arrays are executed with CST MWS. Simulations and measurements of the proposed antennas are compared to each other. Both antennas are used for the transmit and the receive channel either. The sensor topology of the radar system is explained. Furthermore the measurement results of the protoype are presented and discussed.","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":"18 1","pages":"97-110"},"PeriodicalIF":0.4,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42945711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper treats Characteristic Mode Analyses of three-dimensional test objects in the context of EMC. Based on computed Characteristic Modes and mode-specific physical quantities, series expansions for HIRFand DCIinduced surface currents are deduced. The contribution of single Characteristic Modes to surface currents at different test frequencies is analyzed. HIRFand DCI-excitations are compared with regard to their surface current distributions in their resonance region determined by Characteristic Mode Analysis.
{"title":"Characteristic Mode Analysis of surface current distributions on metallic structures exposed to HIRF- and DCI-excitations","authors":"Jan Uckerseifer, F. Gronwald","doi":"10.5194/ars-18-33-2020","DOIUrl":"https://doi.org/10.5194/ars-18-33-2020","url":null,"abstract":"This paper treats Characteristic Mode Analyses of three-dimensional test objects in the context of EMC. Based on computed Characteristic Modes and mode-specific physical quantities, series expansions for HIRFand DCIinduced surface currents are deduced. The contribution of single Characteristic Modes to surface currents at different test frequencies is analyzed. HIRFand DCI-excitations are compared with regard to their surface current distributions in their resonance region determined by Characteristic Mode Analysis.","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":"18 1","pages":"33-41"},"PeriodicalIF":0.4,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44181868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reverberation chambers show transient behaviour when excited with a pulsed signal. The field intensities can in this case be significantly higher than in steady state, which implies that a transient field can exceed predefined limits and render test results uncertain. Effects of excessive field intensities of short duration may get covered and not be observable in a statistical analysis of the field characteristics. In order to ensure that the signal reaches steady state, the duration of the pulse used to excite the chamber needs to be longer than the time constant of the chamber. Initial computations have shown that the pulse width should be about twice as long as the time constant of the chamber to ensure that steady state is reached. The signal is sampled in the time domain with a sampling frequency according to the Nyquist theorem. The bandwidth of the input signal is determined using spectral analysis. For a fixed stirrer position, the reverberation chamber, wires, connectors, and antennas can jointly be considered as a linear time-invariant system. In this article, a procedure will be presented to extract characteristic signal properties such as rise-time, transient overshoot and the mean value in steady state from the system response. The signal properties are determined by first computing the envelope of the sampled data using a Hilbert transform. Subsequent noise reduction is achieved applying a Savitzky–Golay filter. The point where steady state is reached is then computed from the slope of the envelope by utilising a cumulative histogram. The spectral analysis is not suitable to examine the transient behaviour and determine the time constants of the system. These constants are computed applying the method of Prony, which is based on the estimation of a number of parameters in a sum of exponential functions. An alternative to the Prony Method is the Time-Domain Vector-Fit method. In contrast to the first mentioned variant, it is now also possible to determine the transfer function of the overall RC system. Differences and advantages of the methods will be discussed.
{"title":"Approximation and analysis of transient responses of a reverberation chamber by pulsed excitation","authors":"Konstantin Pasche, Fabian Ossevorth, R. Jacobs","doi":"10.5194/ars-18-53-2020","DOIUrl":"https://doi.org/10.5194/ars-18-53-2020","url":null,"abstract":"Reverberation chambers show transient behaviour when excited with a pulsed signal. The field intensities can in this case be significantly higher than in steady state, which implies that a transient field can exceed predefined limits and render test results uncertain. Effects of excessive field intensities of short duration may get covered and not be observable in a statistical analysis of the field characteristics. In order to ensure that the signal reaches steady state, the duration of the pulse used to excite the chamber needs to be longer than the time constant of the chamber. Initial computations have shown that the pulse width should be about twice as long as the time constant of the chamber to ensure that steady state is reached. The signal is sampled in the time domain with a sampling frequency according to the Nyquist theorem. The bandwidth of the input signal is determined using spectral analysis. For a fixed stirrer position, the reverberation chamber, wires, connectors, and antennas can jointly be considered as a linear time-invariant system. In this article, a procedure will be presented to extract characteristic signal properties such as rise-time, transient overshoot and the mean value in steady state from the system response. The signal properties are determined by first computing the envelope of the sampled data using a Hilbert transform. Subsequent noise reduction is achieved applying a Savitzky–Golay filter. The point where steady state is reached is then computed from the slope of the envelope by utilising a cumulative histogram. The spectral analysis is not suitable to examine the transient behaviour and determine the time constants of the system. These constants are computed applying the method of Prony, which is based on the estimation of a number of parameters in a sum of exponential functions. An alternative to the Prony Method is the Time-Domain Vector-Fit method. In contrast to the first mentioned variant, it is now also possible to determine the transfer function of the overall RC system. Differences and advantages of the methods will be discussed.","PeriodicalId":45093,"journal":{"name":"Advances in Radio Science","volume":"18 1","pages":"53-73"},"PeriodicalIF":0.4,"publicationDate":"2020-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42586468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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