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Cheng C.,Beijing Institute of Radio Measurement and Metrology | Cheng C.,National Key Laboratory of Metrology and Calibration Technology | Hong Z.,Beijing Institute of Radio Measurement and Metrology | Chen J.,Beijing Institute of Radio Measurement and Metrology | And 2 more authors.
Key Engineering Materials | Year: 2012

FY-3 meteorological satellite is the new generation of China's polar-orbit meteorological satellite and be hoped to meet the operational weather prediction requirements of china and the global change research. The microwave imaging sounder (MWIS) and the microwave temperature sounder (MWTS) are two of its main payloads. To calibrate the linearity, sensitivity and stability of MWIS and MWTS accurately, the calibration target with temperature adjusted function is studied by Beijing Institute of Radio Metrology & Measurement (BIRMM). The configuration, technical specifications and operational theory of the calibration target is presented in this paper. Because the two PID (Proportional-Integral-Differential) outputs by associating the parameter of liquid nitrogen cooling combined with electric heater is used, the target can provide a temperature adjusted brightness temperature output from 85K to 340K in 10GHz∼90GHz to meet calibration requirements in lab environments. © (2012) Trans Tech Publications. Source


Wang J.,Beijing Jiaotong University | Yang Y.,Beijing Institute of Radio Measurement and Metrology | Miao J.,Beihang University | Chen Y.,National Key Laboratory of Metrology and Calibration Technology
IEEE Transactions on Antennas and Propagation | Year: 2010

Internal calibration source provides reference data for remote sensing system. Realistic calibration source is constructed by finite periodic structure, and hence, the emissivity calculation is different from the infinite periodic array case. In this paper, conventional indirect method based on the scattering field is modified first, so that it can be used to calculate the emissivities of finite homogeneous objects. Subsequently, a new method based on antenna concept is proposed for calculating the differential scattering coefficients and emissivities of the inhomogeneous finite objects. The methods are then applied to finite circular pyramid arrays covered with an absorbing material, and the results are analyzed. Furthermore, the effect of the illuminating scope of incident wave on the emissivity and differential scattering coefficient of circular finite pyramid array is studied. © 2006 IEEE. Source


Cheng C.Y.,Beijing Institute of Radio Measurement and Metrology | Cheng C.Y.,National Key Laboratory of Metrology and Calibration Technology | Li F.,Beijing Institute of Radio Measurement and Metrology | Wu C.B.,Beijing Institute of Radio Measurement and Metrology | And 2 more authors.
Advanced Materials Research | Year: 2012

This paper presents the design for a corrugated conical-horn antenna working in WR06 frequency band and its application in emissivity measurement of microwave radiator. For a calibration target of microwave radiometer, we consider design the corrugated conical-horn antenna to satisfy its measurement requirements of the emissivity of calibration target. The antenna is designed with small flare angle and low VSWR in a frequency range of 150±10GHz. The measurement results for electrical properties of antenna and emissivity of microwave radiator are presented in this paper. The results show that the performance of antenna is fit to the emissivity measurement of radiator of radiometer calibration target. © (2012) Trans Tech Publications, Switzerland. Source


Jie L.,Beijing Institute of Radio Measurement and Metrology | Zhesi W.,Beijing Institute of Radio Measurement and Metrology | Yunmei C.,Beijing Institute of Radio Measurement and Metrology | Yunmei C.,National Key Laboratory of Metrology and Calibration Technology | And 2 more authors.
Proceedings - 4th International Conference on Intelligent Computation Technology and Automation, ICICTA 2011 | Year: 2011

Microwave radiometer is a passive remote sensing instrument, which is used to measure thermal electromagnetic emission from material media. It has been widely used in atmosphere detection, ocean observation, earth observation and other domains. Computer simulation plays an important role in system analysis, design, research and performance testing. This paper firstly presents the radiometer's framework and simulates the waveform from the antenna's input noise signal to integrator's output signal (before A/D convector), Then simulates the linearity of the whole model. The simulation result indicates that the linearity of the radiometer is very well, finally gives the calibration equation of the radiometer. © 2011 IEEE. Source


Yang R.-F.,Beijing Institute of Radio Measurement and Metrology | Zhou T.-Z.,Beijing Institute of Radio Measurement and Metrology | Chen H.-B.,Beijing Institute of Radio Measurement and Metrology | Wang N.-R.,National Key Laboratory of Metrology and Calibration Technology | Gao L.-S.,National Key Laboratory of Metrology and Calibration Technology
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2010

To reduce the size and weight of the hydrogen maser atomic clocks, some useful attempts and related research results about sapphire-loaded cylindrical cavities for hydrogen masers were reported by the Beijing Institute of Radio Metrology and Measurement. The fractional frequency stability of the order of 10 -15 over 10 000 seconds can be realized. However, because of a large frequency-temperature coefficient in a single sapphire bulb in the cavity, further improvement of the stability in the compact hydrogen clock was restricted. In this work, we chose several small single-crystal chips of SrTiO 3 with a large negative frequency-temperature coefficient to compensate the sapphire microwave cavity. Based on the theoretical calculation, the frequency-temperature coefficient in the TE 011 mode of a sapphire cavity associated with several small chips of SrTiO 3 can be greatly reduced. A sapphire-loaded cavity and 8 compensated chips of SrTiO 3 were prepared, and a combined cavity was simulated by finite element method and measured by experiments. When quality factor was kept above 40 000, the frequency-temperature coefficient can be reduced to about 1/5 of its starting value. The experimental results agree very well with the calculation and simulation. Furthermore, this new method was applied in the compact hydrogen maser. Because of the decrease of temperature frequency shift, the hydrogen maser stability at medium- and long- term averaging time from 1 s to 10 5 s has an obvious improvement compared with the our previous results. © 2006 IEEE. Source

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