Analysis Of Wideband Scattering Characteristics Of Antenna Targets For Stepped Frequency Radar

As an important component of radio equipments, antenna has become an active research field in recent years as a result of its special importance on the battlefield and unique radar scattering effects. The antenna scattering analysis can provide important information for anti-radiation seeker to improve the operational capability of anti-radiation weapons. This thesis analyzes three main issues, i.e., antenna scattering mechanisms, antenna wideband radar imaging and antenna wideband electromagnetic feature extraction. The main work is summarized as follows:1. The models of antenna scattering are studied in Chapter 2. Firstly, based on the scattering mechanism of antennas, the antenna structural scattering field and antenna mode scattering field are analyzed. Then three kinds of models for antenna scattering parameters computation are described in detail. Moreover, with the microstrip antenna and horn antenna as examples, the antenna structural scattering field and antenna mode scattering field are separated. Finally, the correctness and consistency of the three calculation models are validated by simulation.2. The antenna echo signal and its one-dimensional imaging methods are studied in Chapter 3 under stepped frequency signal system. Firstly, we take a horn antenna as an example and obtain the one-dimensional high range resolution profile (HRRP) of the antenna scattering field by IFFT. The defocus of the HRRP obtained by IFFT is caused by the nonlinear phase modulation phenomenon of antenna mode scattering. Antenna mode imaging method based on dispersive compensation has been proposed and the mode scattering calculations of horn antenna verifies the validity of the method.3. In Chapter 4, the antenna wideband electromagnetic feature extraction problem is mainly studied. Firstly, taking the parabolic antenna and the horn antenna as examples, we analyze the structural scattering one-dimensional range profile feature of the two types of antenna, which reveals the structural difference of the two antennas; Secondly, according to the periodicity of antenna scattering which includes transmitting and receiving periodic switching and antenna rotation periodicity, the periodic characteristics of antennas are extracted. The electromagnetism computation simulation results indicate the validity of the feature extraction algorithm. Finally, the adaptive Gauss representation (AGR) is used to extract the time-frequency distribution characteristics of antenna mode scattering. Through decomposing the antenna backscattering into point-scattering and resonance, the non-point blur effects in antenna mode scattering imaging have been eliminated. The comparison of electromagnetic calculation simulation results verifies the validity of the algorithm.The final chapter summarizes the main work of the thesis and points out the thesis deficiency and the further research direction.