Feature Extraction And Recognition Of Targets In Ballistic Midcourse In Polarization-Domain

With the development of the radar polarization technology and the equipment of the polarimetric radar, the detection and target reorganization abilities of radar system have been remarkably improved. Nowadays, the polarimetric radar is very important in the air defense and antimissile fields. Under the background of space monitoring and missile defense, some basic and major problems of the polarimetric radar, such as the scattering matrix measurement of dynamic target, the discrimination of active decoys in polarization-domain and the reorganization of missile warhead in the midcourse, are studied in this thesis.The main contents and results of the thesis are as follows:Firstly, a scattering matrix measurement method through pulse-to-pulse polari- zarion switching and a simultaneous scattering matrix measurement method based on frequency shifted pulse signals of the dynamic target are brought forward. Also, the abilities of these methods are analyzed. It is shown that the scattering matrix of the dynamic target can be measured accurately by the interleaved-pulse polarization agile radar and the polarimetric radar adopting frequency shifted pulse waveform under a certain SNR condition. So, the opinion that the scattering matrix of the dynamic target can not be measured by the interleaved-pulse polarization agile radar and the polarimetric radar adopting frequency shifted pulse waveform is rectified. Also, the contribution to the angular glint suppression of target polarization information is quantitative analyzed by the example of a linear target in this thesis.Secondly, the polarization characteristics of active decoys, which are produced by single-polarization and polarization agile repeater jammer, measured by different matrix measurement radar systems are analyzed. It is clear in the results that the characteristics of active decoys measured by the interleaved-pulse polarization agile radar and the single-hit target scattering matrix measurement radar are different, though the active decoys is produced by the same jamming mode. The discrimination methods of active decoys in polarization-domain under narrowband and wideband are produced. Especially, considering the scattering matrix may not be able to be measured accurately in the jamming situation, a target reorganization method based on the inadequate polarization characteristics is given.Thirdly, the micro-motion and scattering matrix characteristics of symmetrical rolling warhead in the midcourse are studied, and the robust parameters of the warhead are extracted. An extraction method of the warhead micro-motion characteristics in midcourse, such as nutation frequency and nutation angle, is presented. An ISAR imaging method of warhead in midcourse is produced base on the micro-motion. Comparing with the ISAR imaging method base on the macrodynamics of ballistic missile presented by most literatures, the correlation time is remarkably reduced by the method in this thesis.The studying results of this thesis are helpful in target detection, imaging and recognition abilities of the air monitoring and missile defense radar systems. The methods of false target discrimination in the polarization domain and scattering matrix measurement of dynamics targets are also useful in the field of battle sensations such as air defense radar and EW.