Different methods of calibrating ultra high frequency(UHF) sensors for gas-insulated substations(GIS) were investigated in the past.The first approach was to use strip lines,triplates and TEM calibration cells.These c...Different methods of calibrating ultra high frequency(UHF) sensors for gas-insulated substations(GIS) were investigated in the past.The first approach was to use strip lines,triplates and TEM calibration cells.These cells had already been in use for years for example to test the electromagnetic compatibility of electronic devices.The smaller the size of the cell,the higher its bandwidth-but the cell should be large enough to not disturb the electric field with the installed sensor under test.To overcome this problem,a calibration procedure using a gigahertz transverse electromagnetic (GTEM) test cell and a pulsed signal source were introduced in 1997.Although this procedure has many advantages and is easy to understand,measurements show several shortcomings of this calibration method.To overcome the disadvantages of the known systems,a calibration cell using a monopole cone antenna and a metallic ground plane were developed and tested.The UHF sensor was placed in a region with minimum distortion of the electric field due to its installation.Experience shows that the new method for calibrating UHF sensors is necessary in order to overcome the limits in the calibration of large sensors and to suppress the propagation of higher order modes and reflections.Due to its surprisingly simple structure,its low price and low overall measurement uncertainty,it is the preferred method for calibrating UHF sensors for GIS applications.展开更多
Radio-frequency identification(RFID)antennas are critical components in wireless communication networks for the Internet of things(IoT).The RFID systems make it possible to realize the dynamic interconnection of vario...Radio-frequency identification(RFID)antennas are critical components in wireless communication networks for the Internet of things(IoT).The RFID systems make it possible to realize the dynamic interconnection of various things.To better summarize the operating principles of the RFID antennas and associate antennas with specific complex applications,a review of RFID systems and antennas is necessary.In this paper,a review of reader antennas for ultra-high frequency(UHF)RFID systems is presented,and the categories of RFID systems are summarized for the first time.The antennas are classified according to the reading region and operating principle.The reading region determines the most crucial performance that should be concentrated on when designing an antenna,while the operating principle affects the current distribution on the surface of the antenna,and further the electromagnetic radiation.By the summary of the RFID systems and antennas,the understanding of future researchers on the operating principles of the RFID antennas could be facilitated,which can be helpful in the advanced design and implementation of RFID antennas.In addition,taking engineering requirements into account,the future prospective of RFID applications is discussed,as well as the challenges to be addressed.展开更多
文摘Different methods of calibrating ultra high frequency(UHF) sensors for gas-insulated substations(GIS) were investigated in the past.The first approach was to use strip lines,triplates and TEM calibration cells.These cells had already been in use for years for example to test the electromagnetic compatibility of electronic devices.The smaller the size of the cell,the higher its bandwidth-but the cell should be large enough to not disturb the electric field with the installed sensor under test.To overcome this problem,a calibration procedure using a gigahertz transverse electromagnetic (GTEM) test cell and a pulsed signal source were introduced in 1997.Although this procedure has many advantages and is easy to understand,measurements show several shortcomings of this calibration method.To overcome the disadvantages of the known systems,a calibration cell using a monopole cone antenna and a metallic ground plane were developed and tested.The UHF sensor was placed in a region with minimum distortion of the electric field due to its installation.Experience shows that the new method for calibrating UHF sensors is necessary in order to overcome the limits in the calibration of large sensors and to suppress the propagation of higher order modes and reflections.Due to its surprisingly simple structure,its low price and low overall measurement uncertainty,it is the preferred method for calibrating UHF sensors for GIS applications.
基金supported by the National Natural Science Foundation of China(61971051)。
文摘Radio-frequency identification(RFID)antennas are critical components in wireless communication networks for the Internet of things(IoT).The RFID systems make it possible to realize the dynamic interconnection of various things.To better summarize the operating principles of the RFID antennas and associate antennas with specific complex applications,a review of RFID systems and antennas is necessary.In this paper,a review of reader antennas for ultra-high frequency(UHF)RFID systems is presented,and the categories of RFID systems are summarized for the first time.The antennas are classified according to the reading region and operating principle.The reading region determines the most crucial performance that should be concentrated on when designing an antenna,while the operating principle affects the current distribution on the surface of the antenna,and further the electromagnetic radiation.By the summary of the RFID systems and antennas,the understanding of future researchers on the operating principles of the RFID antennas could be facilitated,which can be helpful in the advanced design and implementation of RFID antennas.In addition,taking engineering requirements into account,the future prospective of RFID applications is discussed,as well as the challenges to be addressed.
