Subjects: Geosciences >> Space Physics Subjects: Geosciences >> Marine Sciences submitted time 2016-05-03
Abstract： In order to study the feasibility of ocean surface current measurement using radar scatterometer, the system parameters of the traditional scatterometer were modified, the coherent coefficient model and decorrelation factors were derived, and the phase error model was obtained. Moreover, this paper established an end-to-end model to simulate the ocean surface current measurement. The input wind speeds ranged from 2m/s to 21m/s and the wind direction was parallel to the cross track direction. The results show that the current speed standard deviation in along-track and cross-track direction are smaller than 0.1m/s, when the wind speed is greater than 5m/s. And the swath that can be used for current speed inversion is greater than 40%, when the wind speed is larger than 7m/s. The width of effective swath increases with the increase of the wind speeds. After parameters' optimization, communication error was calculated and the results show that the communication error of the modified scatterometer is better than that of the fan-beam, rotating scatterometer in both the low wind speed and high wind speed conditons. � 2015, Chinese Institute of Electronics. All right reserved.
Peer Review Status:
Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-03
Abstract： The scatterometer onboard HY-2 satellite is calibrated using Numerical Ocean Calibration and its retrieval winds after calibration are validated from 130 global buoys and winds from the European Centre for Medium-Range Weather Foresting Numerical Weather Prediction model using triple-collocation during December 2012, resulting in 3112 collocated triplets. The KNMI QC flag is used to collocate the data without rain efforts. It is found that functional relationship employing the error-in-variables method is more accuracy than that using linear regression for the validation of retrieval wind from HY-2 scatterometer. Moreover, using the wind component domain is confirmed to be favourable. It is shown that the uncertainties after ocean calibration is less than 0.15dB, resulting in 0.2m/s systematic wind effects. For both zonal and meridional winds, the similar wind fields comparing with buoys and ECMWF indicate that the effective of the calibration and high quality of the retrieval winds. �2015, Chinese Institute of Electronics. All right reserved.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-03
Abstract： Millimeter-wave space-borne antennas with multi-band and multi-polarization have many advances such as high gain,low side-lobe,high beam efficiency and low loss.The operating frequency of the antenna includes 18.7,23.8 and 37.0 GHz.The use of common feed system has significance for saving volume and enhancing structure stiffness.And the ring-loaded corrugated conical horn can cover octave bandwidth.The orthomode transducer(OMT)with new turnstile junction and frequency divider was employed to separate dual polarizations signals and then divide different frequencies into their own receivers,respectively.The cross polarization levels are -32.6,-31.6 and -25.0 dB in 18.7,23.8 and 37.0 GHz,respectively.The side lobe levels are -21,-30 and -30 dB.Due to compact structure and multiple observations for one target,the simulation result demonstrates the design of feed system is suitable to space-borne antennas.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-03
Abstract： To realize remote sensing at sub-millimeter wavelengths,a 450 GHz sub-harmonic mixer was studied. An anti-parallel pair of Schottky diodes is the key component in the mixer. The length of the diodes is 74 mum,and the cutoff frequency of diodes is up to 8 THz. The suspended microstrip matching circuit was built on quartz,and the metal block was cut into two halves. The diode embedding impedance was calculated. The diode package and the matching circuit were integrated in the mixer model. The predicted single side band (SSB) conversion loss is 8. 0 dB,with 4 mW of local oscillator power. Measured results indicate that the lowest measured SSB conversion loss is 14. 0 dB, with 5 mW of local oscillator power. The loss is below 17. 0 dB in the band from 433 ~ 451 GHz,with a 3 dB bandwidth of 18 GHz.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-03
Abstract： A novel single layer microstrip reflectarray element with multi-resonance structure is proposed in this paper.HFSS soft ware is used to analyze the reflect phase for the designed element.About 430皉eflect phase range is obtained with the reflect phase curve nearly linear.A microstrip reflectarray composed of the proposed element is designed for Ku band and a Vivaldi antenna is used as the feed.The results indicate that the gain reaches 27.1 dB at the center frequency,and the half power beamwidth is 4.96�The gain changes less than 2 dB in the range of 12~15.5GHz,which shows that the reflectarray has wide band.The Vivaldi antenna and the reflectarray is manufactured and tested,and a well coincide is obtained between the simulation results and the test results.
Peer Review Status:Awaiting Review
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