A finite domain time difference (FDTD) and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD's ...A finite domain time difference (FDTD) and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD's near to far field transformation to obtain the fields in Fresnel region and then applies the second-derivative method to calculate the phase center. The adoption of FDTD efficiently overcomes the difficulties arising from the existing calculation methods' requirements for the radiation analytical formula of some complex antennas, which makes the existing second-derivative method more applicable in engineering. Also, FDTD increases the precision owing to the superposition field calculation from its extrapolation. The correctness of this proposed method is certified with typical examples and the phase center in the Fresnel region of a microwave radiometry calibration corrugate horn antenna is evaluated with the key features.展开更多
A scanning and uniform array architecture with large spacing,low complexity and high scalability is presented for high integration massive array applications.It is constructed by offset phase center elements arranged ...A scanning and uniform array architecture with large spacing,low complexity and high scalability is presented for high integration massive array applications.It is constructed by offset phase center elements arranged in a uniform and regular way,but its spacing can be larger than that of traditional arrays.An ideal model of the offset phase center element is established and its far-field distribution is derived.To suppress grating lobes,the phase center of any element is designed to be movable without changing its physical position.Using genetic algorithm(GA),a new constraint condition limiting the number of phase center changes is proposed to solve the objective function of the minimum values of grating lobes(GLs)and side lobes(SLs).It is shown that the optimal results can be achieved by two changes of phase centers.A multimode circular patch is developed and designed,and characteristics of the offset phase center are analyzed and verified.A prototype array of 12×12 offset phase center elements is implemented based on multi-mode circular patches.Full wave simulation results of radiation patterns show that the level of grating lobes is suppressed at least 7dB with 1.12λ spacing,while the scanning angle is 20°.展开更多
The correction for antenna phase center is considered in processing Global Positioning System (GPS) data collected from a network of GPS ultra-short baselines. Compared with the leveling measurements, the GPS result...The correction for antenna phase center is considered in processing Global Positioning System (GPS) data collected from a network of GPS ultra-short baselines. Compared with the leveling measurements, the GPS results show that the relative vertical offsets for the pairs of GPS receiver antenna phase centers still exist, although absolute calibration of the antenna phase center variations (PCVs) has been considered. With respect to the TPS CR.G3 antenna, the relative vertical offset for the LEI AT504 antenna is 8.4 mm, the offset for the ASH701945C_M antenna is 5.5 mm, and those for the ASHY00936E_C and ASH701945B_M antennas are approximately between 2 mm and -3 mm. The relative offsets for the same type of antennas are approximately 1 mm. By correcting the absolute PCVs, the existing relative offset becomes negligible for horizontal positioning.展开更多
The characteristics of the phase centers of electromagnetic horns having nearlysymmetric pattern are presented analytically.It is proved that the phase center on the φ=45°plane coincides with the average phase c...The characteristics of the phase centers of electromagnetic horns having nearlysymmetric pattern are presented analytically.It is proved that the phase center on the φ=45°plane coincides with the average phase center,and if a single plane phase center is used to definethe horn phase center approximately,the φ=45° plane phase center will be the best choice.展开更多
A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for ...A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for solving this model is described.By using thismethod,the phase center of corrugated horn is discussed and calculated,and the variation of thephase center with distance and operating frequency is given.展开更多
In determining the orbits of low Earth orbit (LEO) satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset (PCO) and phase center variations (PCVs) are gradually becoming a maj...In determining the orbits of low Earth orbit (LEO) satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset (PCO) and phase center variations (PCVs) are gradually becoming a major limiting factor for continued improvements to accuracy. Shiyan 3, a small satellite mission for space technology experimentation and climate exploration, was developed by China and launched on November 5, 2008. The dual-frequency GPS receiver payload delivers 1 Hz data and provides the basis for precise orbit determination within the range of a few centimeters. The antenna PCO and PCV error characteristics and the principles influencing orbit determination are analyzed. The feasibility of PCO and PCV estimation and compensation in different directions is demonstrated through simulation and in-flight tests. The values of receiver antenna PCO and PCVs for Gravity Recovery and Climate Experiment (GRACE) and Shiyan 3 satellites are estimated from one month of data. A large and stable antenna PCO error, reaching up to 10.34 cm in the z-direction, is found with the Shiyan 3 satellite. The PCVs on the Shiyan 3 satellite are estimated and reach up to 3.0 cm, which is slightly larger than that of GRACE satellites. Orbit validation clearly improved with independent k-band ranging (KBR) and satellite laser ranging (SLR) measurements. For GRACE satellites, the average root mean square (RMS) of KBR residuals improved from 1.01 cm to 0.88 cm. For the Shiyan 3 satellite, the average RMS of SLR residuals improved from 4.95 cm to 4.06 cm.展开更多
A trajectory integrator is developed based on a particle's guiding center Hamiltonian. It is verified by a series of benchmarks, which are in good accordance with theoretical prediction. This integrator can be used a...A trajectory integrator is developed based on a particle's guiding center Hamiltonian. It is verified by a series of benchmarks, which are in good accordance with theoretical prediction. This integrator can be used as the guiding center trajectory integrator of a particle-in-cell simulation platform, such as the newly developed VirtEx. It can also be used as a stand-alone tool to investigate particle dynamics in a given background field.展开更多
Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing (QIP) tasks. Recently, a novel solid-state cavity quantum electrodynamics (QED) ...Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing (QIP) tasks. Recently, a novel solid-state cavity quantum electrodynamics (QED) system, in which the nitrogen-vacancy (NV) center in diamond is coupled to a microtoroidal resonator (MTR), has been proposed as a poten- tial system for hybrid quantum information and computing. By virtue of such systems, we present a scheme to realize a nonlocal N-qubit conditional phase gate directly. Our scheme employs a cavity input-output process and single-photon interference, without the use of any auxiliary entanglement pair or classical communication. Considering the currently available technologies, our scheme might be quite useful among different nodes in quantum networks for large-scaled QIP.展开更多
Influence of recombination centers’ changes on the form of phase portraits has been studied. It has been shown that the shape of the phase portraits depends on the concentration of semiconductor materials’ recombina...Influence of recombination centers’ changes on the form of phase portraits has been studied. It has been shown that the shape of the phase portraits depends on the concentration of semiconductor materials’ recombination centers.展开更多
A novel simplified method is presented to design FIR filter with controllable center frequency. The properties of transfer curves for all-phase filters are illustrated under 3 windowing conditions. By combining single...A novel simplified method is presented to design FIR filter with controllable center frequency. The properties of transfer curves for all-phase filters are illustrated under 3 windowing conditions. By combining single-window all-phase filter design steps and double phase-shift combination, a series of design formulas for point-pass filter, notch filter, band-pass filter and band-stop filter are derived, thus the design computation complexity is greatly reduced. Experiments prove that the center frequency of all the filters can be accurately specified at arbitrary position by adjusting frequency parameters m and λ.展开更多
基金the National Key Laboratory of Metrology and Calibration Technology
文摘A finite domain time difference (FDTD) and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD's near to far field transformation to obtain the fields in Fresnel region and then applies the second-derivative method to calculate the phase center. The adoption of FDTD efficiently overcomes the difficulties arising from the existing calculation methods' requirements for the radiation analytical formula of some complex antennas, which makes the existing second-derivative method more applicable in engineering. Also, FDTD increases the precision owing to the superposition field calculation from its extrapolation. The correctness of this proposed method is certified with typical examples and the phase center in the Fresnel region of a microwave radiometry calibration corrugate horn antenna is evaluated with the key features.
基金This work was supported by National Natural Science Foundation of China(No.U19B2028).
文摘A scanning and uniform array architecture with large spacing,low complexity and high scalability is presented for high integration massive array applications.It is constructed by offset phase center elements arranged in a uniform and regular way,but its spacing can be larger than that of traditional arrays.An ideal model of the offset phase center element is established and its far-field distribution is derived.To suppress grating lobes,the phase center of any element is designed to be movable without changing its physical position.Using genetic algorithm(GA),a new constraint condition limiting the number of phase center changes is proposed to solve the objective function of the minimum values of grating lobes(GLs)and side lobes(SLs).It is shown that the optimal results can be achieved by two changes of phase centers.A multimode circular patch is developed and designed,and characteristics of the offset phase center are analyzed and verified.A prototype array of 12×12 offset phase center elements is implemented based on multi-mode circular patches.Full wave simulation results of radiation patterns show that the level of grating lobes is suppressed at least 7dB with 1.12λ spacing,while the scanning angle is 20°.
基金supported by the Science for Earthquake Resilience(XH14070Y,XH15064Y)the China NationalSpecial Fund for Earthquake Scientific Research in Public Interest(201208009)
文摘The correction for antenna phase center is considered in processing Global Positioning System (GPS) data collected from a network of GPS ultra-short baselines. Compared with the leveling measurements, the GPS results show that the relative vertical offsets for the pairs of GPS receiver antenna phase centers still exist, although absolute calibration of the antenna phase center variations (PCVs) has been considered. With respect to the TPS CR.G3 antenna, the relative vertical offset for the LEI AT504 antenna is 8.4 mm, the offset for the ASH701945C_M antenna is 5.5 mm, and those for the ASHY00936E_C and ASH701945B_M antennas are approximately between 2 mm and -3 mm. The relative offsets for the same type of antennas are approximately 1 mm. By correcting the absolute PCVs, the existing relative offset becomes negligible for horizontal positioning.
文摘The characteristics of the phase centers of electromagnetic horns having nearlysymmetric pattern are presented analytically.It is proved that the phase center on the φ=45°plane coincides with the average phase center,and if a single plane phase center is used to definethe horn phase center approximately,the φ=45° plane phase center will be the best choice.
文摘A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for solving this model is described.By using thismethod,the phase center of corrugated horn is discussed and calculated,and the variation of thephase center with distance and operating frequency is given.
基金co-supported by the National Natural Science Foundation of China (Nos.61370013 and 91438202)the High Resolution Earth Observation System Major Special Project Youth Innovation Foundation of China (No.GFZX04060103)
文摘In determining the orbits of low Earth orbit (LEO) satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset (PCO) and phase center variations (PCVs) are gradually becoming a major limiting factor for continued improvements to accuracy. Shiyan 3, a small satellite mission for space technology experimentation and climate exploration, was developed by China and launched on November 5, 2008. The dual-frequency GPS receiver payload delivers 1 Hz data and provides the basis for precise orbit determination within the range of a few centimeters. The antenna PCO and PCV error characteristics and the principles influencing orbit determination are analyzed. The feasibility of PCO and PCV estimation and compensation in different directions is demonstrated through simulation and in-flight tests. The values of receiver antenna PCO and PCVs for Gravity Recovery and Climate Experiment (GRACE) and Shiyan 3 satellites are estimated from one month of data. A large and stable antenna PCO error, reaching up to 10.34 cm in the z-direction, is found with the Shiyan 3 satellite. The PCVs on the Shiyan 3 satellite are estimated and reach up to 3.0 cm, which is slightly larger than that of GRACE satellites. Orbit validation clearly improved with independent k-band ranging (KBR) and satellite laser ranging (SLR) measurements. For GRACE satellites, the average root mean square (RMS) of KBR residuals improved from 1.01 cm to 0.88 cm. For the Shiyan 3 satellite, the average RMS of SLR residuals improved from 4.95 cm to 4.06 cm.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11675257,11675256 and 11705275the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB16010300+2 种基金the Key Research Program of Frontier Science of Chinese Academy of Sciences under Grant No QYZDJ-SSW-SYS016the External Cooperation Program of Chinese Academy of Sciences under Grant No 112111KYSB20160039the National Magnetic Confinement Fusion Science Program of China under Grant Nos 2013GB111003 and 2013GB112011
文摘A trajectory integrator is developed based on a particle's guiding center Hamiltonian. It is verified by a series of benchmarks, which are in good accordance with theoretical prediction. This integrator can be used as the guiding center trajectory integrator of a particle-in-cell simulation platform, such as the newly developed VirtEx. It can also be used as a stand-alone tool to investigate particle dynamics in a given background field.
基金Project supported by the National Fundamental Research Program of China(Grant No.2010CB923202)the Fundamental Research Funds for the Central Universities,Chinathe National Natural Science Foundation of China(Grant Nos.61177085,61205117,and 61377097)
文摘Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing (QIP) tasks. Recently, a novel solid-state cavity quantum electrodynamics (QED) system, in which the nitrogen-vacancy (NV) center in diamond is coupled to a microtoroidal resonator (MTR), has been proposed as a poten- tial system for hybrid quantum information and computing. By virtue of such systems, we present a scheme to realize a nonlocal N-qubit conditional phase gate directly. Our scheme employs a cavity input-output process and single-photon interference, without the use of any auxiliary entanglement pair or classical communication. Considering the currently available technologies, our scheme might be quite useful among different nodes in quantum networks for large-scaled QIP.
文摘Influence of recombination centers’ changes on the form of phase portraits has been studied. It has been shown that the shape of the phase portraits depends on the concentration of semiconductor materials’ recombination centers.
基金Supported by National Natural Science Foundation of China (No. 60802048)New Teacher PhD Programs Foundation of Ministry of Education of China (No. 200700056105)
文摘A novel simplified method is presented to design FIR filter with controllable center frequency. The properties of transfer curves for all-phase filters are illustrated under 3 windowing conditions. By combining single-window all-phase filter design steps and double phase-shift combination, a series of design formulas for point-pass filter, notch filter, band-pass filter and band-stop filter are derived, thus the design computation complexity is greatly reduced. Experiments prove that the center frequency of all the filters can be accurately specified at arbitrary position by adjusting frequency parameters m and λ.