Approach And Out-Field Experimental Study On Repeater Deception Jamming Suppression With Frequency Diverse Array Radar

During the development of radar technology,electronic countermeasures is always an eternal theme.In various kinds of jammings,the deceptive jamming,deriving from the use of digital radio frequency memory(DRFM)which can accurately replicate radar transmission waveforms,is of great attraction.The fake targets formed by deceptive jammings can easily be judged as real targets by radars due to its high coherence with radar echo signals.These fake targets will undoubtedly degradate the performance of searching and tracking real targets for radars.The frequency diversity array(Frequency Diverse Array,FDA)radar introduces a frequency offset which is much smaller than the working carrier frequency between the antenna elements.So that the emission pattern is not only related to the angle,but also related to the distance.The degree of freedom in the distance dimension provides an effective new way to suppress main lobe deceptive jamming.At present,the FDA radar-related technology is still in the theoretical research stage.In order to make the anti-jamming technology of frequency diversity array radar further practical,in this paper,combining with practical engineering applications and aiming at the problem of main lobe spoofing jamming suppression in complex electronic environments,the research and experimental verification of the key technologies of frequency diversity array radar main lobe spoofing jamming suppression are carried out.The main work can be summarized as:1.A frequency diversity array radar model is constructed,and the space-time-frequency multi-dimensional characteristics of deceptive jamming are analyzed.Firstly,a frequency diversity array radar model is established,and the characteristics of the FDA radar emission pattern are analyzed.Secondly,combining FDA and MIMO technology,the form of target echo signal under FDA-MIMO system is given.The difference of distribution in transmitreceive two-dimensional domain.Finally,the deceptive jamming signal is recorded through the field experiment.After processing the measured data,it can be concluded that the jamming signal can effectively jam the radar system by means of distance and speed modulation.2.In view of the experimental verification of the external field anti-jamming technology carried out in this paper,the development of the experimental principle prototype of the frequency diversity array radar is carried out,and the design of the signal acquisition and storage subsystem and the realization of the radar system channel correction were completed.Firstly,the overall architecture design of the radar experimental system is expounded,including the overall framework and the functions of each sub-system;Secondly,it introduces the hardware composition of the board card of the signal acquisition and storage subsystem,and designs and implements the key functional modules in the subsystem.The logic simulation of the key modules is carried out to verify the validity of the design;Finally,in order to ensure the anti-jamming performance of the radar experimental system,the channel correction function of the frequency diversity array radar experimental system is completed,which lays a foundation for the validity of the measured data in the field experiment.3.Aiming at the problem that the main lobe spoofing jamming is difficult to suppress,the anti-jamming theory of non-adaptive beamforming under FDA-MIMO system is tested and verified in combination with practical engineering.Firstly,the basic principle of nonadaptive beamforming anti-jamming under FDA-MIMO system is studied.According to the relationship between the interference transmission frequency and the zero position of the non-adaptive pattern,the design of the frequency step is studied,so that the interference can be eliminated by setting zero.suppress;Secondly,the frequency diversity array radar experimental system is built,and the anti-jamming field experiment scheme is designed,and the field experiment is carried out under this scheme,and finally the measured data collected in the experiment is processed to verify the results.Data processing includes multi-channel receiving correction,multi-waveform separation,clutter suppression and anti-jamming,etc.The experimental results prove the feasibility of FDA radar anti-repeater deception jamming in practical engineering.4.Aiming at the problem that the anti-jamming performance of non-adaptive beamforming is reduced due to systematic errors in practical engineering,the adaptive beamforming antijamming under FDA-MIMO system is proposed in combination with practical engineering,and field experiments are carried out.Firstly,the basic principle of adaptive beamforming anti-jamming is discussed,and it is difficult to accurately estimate the interference covariance matrix due to the pseudo-random distribution of false targets in the distance dimension.Furthermore,the sample selection method based on orthogonal projection is used to select suitable samples.So as to achieve accurate estimation of interference covariance matrix.Finally,the field experiment of the frequency diversity array radar system is carried out.The results of the field experiment show that the anti-jamming performance of the adaptive beamforming is improved by 20 d B compared with the non-adaptive beamforming.