Radar Target Poles Extractions And Target Indentification In Resonance Region

The electromagnetic scattering characteristic of target in the resonance region is obvious,and the echo will usually carry the resonance-characteristic of target.The pole feature is a kind of primitive information of the object,which is only related to the size,material and shape of the object,and has nothing to do with other external factors such as incidence direction or polarization mode.Using the pole feature to recognize the target can greatly reduce the template requirement of the feature library.In this thesis,the pole feature is firstly acquired by establishing the target echo model and extracting the poles of aircrafts,then analyzed and used to recognize target efficiently.This thesis firstly uses electromagnetic simulation software to model and split the target,and to construct the echo of targets,then uses the Matrix pencil method to extract poles of targets from the echo preliminarily.In order to make the extraction results more accurate,the relevant parameters of the Matrix pencil method are optimized and selected,and the preliminary extraction results are further purified.The results of single-direction poles extraction are susceptible to interference,hence,multi-direction poles are integrated to get the final pole.In the thesis,poles extraction and purification simulation are carried out for thin conductor with theoretical poles.The extraction results correspond to the theoretical value.For complex objects,poles extraction results of multiple orientations can be aggregated and coincided,which verifies the rationality of the extraction process.Then the relationship between target poles and frequency band selection and frequency domain peak is studied.The simulation shows that the poles extraction is incomplete when the frequency band of echo data cannot cover the frequency needed to extract the poles,and the number of missing poles corresponds to the number of spectral peak in the missing frequency band.In the case of incomplete frequency band,the target pole can be extracted only through the peak data.Poles are also divided into internal poles and external poles.The closed hollow target can extract the external poles,while the open target can extract the internal poles in addition to the external poles,and the internal poles have a one-to-one correspondence with the echo peaks in the frequency domain,which increases the shortcut for the extraction of the poles and provides more possibilities for the identification method related to the pole feature.In the application of target identification,the thesis constructs the E-pulse based on the pole of targets.After convolving the E-pulse with the target echo,it will be partially eliminated to zero.Based on this feature,the E-pulse can classify the target and avoid the effect of noise in real-time poles extraction process.In this thesis,using aircrafts with fewer feature templates to perform recognition simulation can get a high recognition rate.Because the poles extraction and recognition are susceptible to the influence of electromagnetic scattering intensity,head and tail directions of stealth aircraft have a poor recognition result.To solve this problem,this thesis proposes a comprehensive recognition scheme for multi-feature fusion.Simulation results show that the recognition results of the scheme are reliable,and the requirements for the feature library are looser.A small number of feature templates can achieve better recognition effects.