分类： 地球科学 >> 空间物理学 提交时间： 2017-03-10
摘要：Brightness temperature change of observation target in one imaging period will introduce image blur to the retrieved image of geostationary interferometric microwave sounder (GIMS), which uses rotating circular array to realize time-sharing sampling other than snap-shot to reduce system complexity but meanwhile resulting in a relatively long imaging period. In this paper, an interpolation method utilizing time sequence of visibilities collected by time-sharing sampling is presented. The method is verified through a simulation system that simulates GIMS's observation process in viewing a series of near real case brightness temperature maps modeled by FNL/WRF/RTTOV method. Results show that the interpolation method can de-blur the image and reduce imaging error to the degree of snap-shot imaging. �2016 IEEE.
分类： 地球科学 >> 空间物理学 提交时间： 2017-03-10
摘要：In this paper, a novel X-band broadband single-layer unit cell with attached phase-delay lines for reflectarray antennas is proposed to surmount the limitation of the reflectarray bandwidth. The unit cell is composed of three circular rings, each with a pair of gaps which are mutually placed orthogonally, and two identical circular phase-delay lines are attached to the outer ring to provide the required reflection phase. After the simulation for the unit cell carried out, a large reflecting phase range of about 600�and almost linear phase curve are achieved at the center frequency of 10 GHz. Parallel phase curves of different frequencies ranging from 9 GHz to 12 GHz are also obtained. To validate the broadband performance of the proposed unit cell, a 9 �9 center-fed reflectarray antenna operating at X band is designed and simulated. Simulation results show that the designed antenna has 34% 1-dB gain bandwidth, which demonstrates that an obvious improvement on the bandwidth has been achieved compared to the previous works. Besides, the cross-polarization level is decreased to -40 dB by a mirror symmetric element arrangement.
分类： 地球科学 >> 空间物理学 提交时间： 2017-03-10
摘要：Cloude-Pottier incoherent target decomposition (ICTD) and Touzi ICTD has been widely applied as a popular approach to interpret the scattering characteristics of a target in polarimetric synthetic aperture radar (PolSAR) data processing. However, they have a common drawback, i.e. proliferation of parameters (PoP) is unavoidable. Paladini et al. solved this problem by developing an orientation-invariant ICTD based on the coherency matrix under circular polarization basis. As an alternative to Paladini decomposition, we proposed a novel ICTD based on the frequently used coherency matrix under linear polarization basis. The proposed method can also avoid the problem of PoP, and avoid the ambiguity of alpha angle of Paladini decomposition as well. Real PolSAR data is processed to validate the proposed decomposition.
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