The Analysis And Application Of Polarization Effect In Mirrored Aperture Synthesis Radiometry

The accurate prediction of the extreme climate is very urgent to all countries due to the enormous destruction of the unexpected meteorological disasters.The key problem is how to achieve the high spatial resolution of the remote sensing of atmospheric temperature and humidity in geostationary orbit.Due to the disadvantages of the real aperture radiometer and the synthetic aperture radiometer,there is no effective method to solve the problem of the high spatial resolution in the geostationary orbit.In order to solve the high-resolution passive microwave remote sensing of atmospheric temperature and humidity in the geostationary meteorological satellites,mirrored aperture synthesis was proposed.Its main concept named is making use of a small antenna array and the two-dimensional mirror principle to provide a large virtual mirrored antenna array,so it can supply high spatial resolution with a small array.The method has been studied by Nanchang University and Huazhong University of Science and Technology.Its basic theory has been verified by simulation and experiment.However,in the process of research,it is found that the polarization effect in mirrored aperture synthesis has not been fully analyzed and verified by experiment.In this thesis,the impact of polarization on the correlation output of mirrored aperture synthesis was analyzed.Theoretical formulas of reflection signal on the interface between ideal medium and ideal conductor,and theoretical formulas of cross-correlation of pairs of antennas under different polarization conditions are deduced.Simulation and verification experiments are carried out by 8-channel one-dimensional and two-dimensional mirrored aperture synthesis prototype working at Ka band developed by Nanchang University.The results of fringe pattern experiment are basically consistent with the theoretical derivation and simulation results,which verifies the influence of different polarizations of electromagnetic wave on the mirrored aperture synthesis,and further improves the theoretical basis of mirrored aperture synthesis.For the polarization problem on direction finding,the feasibility of realizing direction finding of all polarized signals by mirrored aperture synthesis are discussed.Single point source imaging experiments and two point sources imaging simulation experiments are carried out.Experimental results and performance analysis show that circularly polarized antenna array can receive various polarized signals based on mirrored aperture synthesis system,which can achieve high-precision direction finding and obtain polarization state of signal.