Application And Analysis Of Spatial Polarization Characteristics For Antenna

Under battleground of the complicated electromagnetic(EM) environments, in order to fully exploit and utilize the polarization information of EM waves and radar antenna, that is, to let the radar system can adapt complicated and adverse battleground environments with intelligent survival and combat capability, improving the polarization theory and utilizing the EM information sufficiently are becoming a urgent mission in radar polarization information processing technique domain.A completely new concept of spatial polarization charscteristics(SPC) of antenna is proposed in this thesis. The connotation and representation methods of SPC are constructed. Thereby, using the SPC of antenna, the target's polarization characteristic measurement, anti-active jamming and decoy discrimination have been studied. The radar polarization information processing technology is extended and the polarization theory is enriched.The main contributions of the thesis are as follows:In theory, with the guidance of instantaneous polarization theory, the SPC of antennas have been studied, which is not only the extension and evolution of polarization theory but also provides theoretical basis and powerful tools for the application of antenna's SPC. The main contents include three aspects: (1) The representation framework of antenna's SPC are established including the connotation, classical description and spatial instantaneous polarization characteristics. (2) Combining with theoretical derivation and computer simulation, system analysis is done for the SPC of various radar antennas such as short-dipole, orthogonal-dipole, coil antenna, helix antenna, waveguide radiator, horn antenna, parabolic antenna etc. for the first time. Then, some meaningful conclusions are presented. (3) Utilizing the microwave dark room measured data, the SPC of a practical jammer antenna and a parabolic antenna are analyzed. The variation of actual antennas'polarization in space is more obviously than theoretical results although is consistent in essential. On the basis of this, four typical SPC models for antenna are established. This work not only proves the existence but also reveals the internal evolution rule of antenna's SPC. It provides theoretical foundations and technical supports for the application of antenna's SPC such as polarimetric scattering matrix(PSM) measurement, polarization decoy discrimination and interference suppression.In application, aiming at mechanical scanning radar system, using radar antenna's SPC and advanced signal processing methods, the thesis made an effort to improving the anti-jamming and target identification abilities of air defense radar in complex EM environment by exploiting the polarization information in radar equipments utmost. The main achievements include two aspects: (1) A novel method for estimating the polarization state of incoming EM wave is put forward by using the SPC of antenna. Firstly, the algorithm performance is analyzed theoretically such as the feasibility, stability and validity. Then, the influence factors, the application field and the main improving way of the algorithm are analyzed by computer simulation. Finally, in order to suppressing the noise jamming, a new method of adaptive polarization filtering is designed. Performance of this polarization filter has been analyzed theoretically and tested by simulation. (2) Based on the SPC of antenna, two novel PSM measurement methods are proposed. According to the differences in the signal processing method of the received echo, the two algorithms are named as'time-domain PSM measurement'and'frequency-domain PSM measurement'respectively. Combined with microwave dark room measurement data, performance of the two algorithms has been analyzed. Then, the distinguishing of fixed-repeater active decoy in polarization field is researched. The validity of the polarization discrimination method has been tested.The most significant point is the idea and method, which is brought out based on the SPC of radar antenna, is a breakthrough compared with the traditional PSM methods. Not need two orthogonal polarization channels, the PSM measurement can be implemented using just one polarization channel. Compared with abandoning the current equipments and developing entirely new radar systems in U.S. and other developed countries, although there is some inherent difference in performance, the innovative means can greatly reduce the development time and production cost. Adapt to the weapon equipments development characteristics of our country at present and for a long time in the future, the methods will improve the anti-jamming and intelligent recognition abilities greatly.