| In modern information warfare, stealth technology has become one of the main threats of air defense radar system. It has put forward a great challenge to the survival and detection capability of the radar. Therefore,it is significant to study on the anti-stealth technology. The important impetus to improve the anti-stealth capability of airborne radar is the frequency resonance characteristics and polarization characteristics of the stealth targets. In addition, improving the detection capability of the existing radars and exploring new working mode of radars are also important research directions. This thesis originates from a certain type of early warning aircraft project to research on frequency optimization and application of airborne early warning radar.In this thesis, the main frequency band studied is from VHF(Very High Frequency) band to X band(i.e. 30MHz-12GHz). Firstly, the frequencies are divided into two bands by 1GHz to expand researches, respectively. And then, the optimization and application of the RCS fluctuation model of stealth aircraft are studied. Lastly, the possibility is explored to combine the low and high frequency for anti-stealth. The main contributions of this thesis are:1) In low-frequency band, the CST(Computer Simulation Technology) simulation platform is used to sample the RCS(Radar Cross Section) data of two stealth aircrafts. Using frequency and polarization characteristics of stealth aircraft RCS, we design a set of complete anti-stealth frequency selection strategy. The optimal anti-stealth frequencies of VHF band and UHF(Ultra High Frequency) band are selected to improve the anti-stealth capability of early warning radar.2) For the selected specific low-frequency points, the optimization and application of the RCS fluctuation model of stealth aircraft are studied. The posterior parameter estimators of the Chi-square, the lognormal and the Legendre models are derived in the Bayesian framework. Then the MCMC(Markov Chain Monte Carlo) sampling algorithm is adopted to calculate the parameter estimates by constructing Markov chains. Therefore, the fitting accuracies of the three models are improved. In addition, the relation between the RCS fluctuation models and radar detection is also analyzed.3) In high-frequency band, the relation between the wavelength and the maximum radar detection range is derived from four aspects, i.e. the antenna gain, the transmission loss, the accumulation time and the detection threshold. Besides, the relation between radar detection range and frequency is obtained by the numerical simulation of the detection range, and the anti-stealth frequency of the high frequency band is selected by the deep mechanism analysis.4) To combine low and high frequency band for anti-stealth, an intelligent closed loop system is proposed to solve the problem of active disturbance in low frequency band. In order to improve the measurement accuracy of low-frequency radar, a low and high dual band working mode is proposed, and a dual band matching tracking condition is derived. In addition, the dual band cooperative work mode is analyzed briefly, and the solutions to the dual band adaption problem and ultra wide band problem are proposed.In this thesis, according to the characteristics of different frequency bands, the optimum anti-stealth frequencies are selected by reasonable frequency selection methods. And in-depth studies have been accomplished aiming at the low-frequency RCS fluctuation model optimization problem and the anti-stealth problem of dual band, which has certain reference value for the engineering application of radar anti-stealth. |
PDF Full Text Request