Research On Clutter Suppression Approaches For FDA-MIMO Radar

Frequency Diverse Array(FDA)technology has been applied to radar systems.In recent years,the combination of Frequency Diverse Array(FDA)radar and Multiple-Input Multiple-Output(MIMO)technology has become a new institutional radar was proposed.The FDA-MIMO radar adds a frequency increment to the transmitting array element,and its transmitting domain steering vector is distance dependent.Using this feature,this thesis carried out research on clutter suppression methods based on FDA-MIMO radar,focusing on solving key issues such as optimal frequency offset selection,robust main lobe clutter suppression,and range ambiguity clutter suppression.The main contents are summarized as follows:1.Derived a multiple-input multiple-out radar echo signal model based on frequency diverse array system.After that,the distribution characteristics of the target signal and clutter in the transmit-receive two-dimensional spatial frequency domain under the FDA-MIMO radar system have been studied,and the model for clutter suppression based on FDA-MIMO radar is established.2.In order to address the problem that the influence of fixed frequency increment on the clutter suppression performance of traditional Frequency Diverse Array radar,a approach for selecting the optimal frequency increment of FDA-MIMO radar based on weighted modulus and genetic algorithm is proposed.Based on the establishment of the FDA-MIMO radar echo signal model,the space-time distance modeling method under the FDA system is used to perform adaptive clutter suppression through the integrated information of spatial angle,distance and Doppler.The simulation experiment shows that the FDA-MIMO radar has a better clutter suppression effect through the optimal frequency increment estimation.3.Focused on the problem that traditional beamforming cannot effectively cope with the error of the target and clutter,which results in the performance degradation of the space-time adaptive processing(STAP)approach,a robust STAP main lobe clutter suppression approach based on FDA-MIMO radar is proposed.Based on the robust adaptive beamforming(RAB-SDP)algorithm of positive semi-definite programming,an optimal objective function model is established,and the optimal weight vector is obtained by solving the Semi Definite Programing(SDP)problem.Simulation experiments show that the improved RAB-SDP compared with the Minimum Variance Distortionless Response(MVDR)diagonal loading approach,the traditional Linearly Constrained Minimum Variance(LCMV)approach and the worst-performing optimization(WCPO)approach,the proposed approach has improved beam main lobe shape preservation,output signal-tonoise ratio and two-dimensional response clutter suppression performance.4.Focused on the problem that the range ambiguity clutter problem faced by FDA radar,the approach based on FDA-MIMO radar for the range ambiguity clutter suppression has been studied.Based on the establishment of the forward-looking array radar signal model under the FDA-MIMO system,the range ambiguity clutter can be effectively separated after the secondary range-dependent compensation and Doppler compensation.The approach of Joint Domain Localised(JDL)dimensionality reduction and the approach based on sparse dimensionality reduction are respectively adopted that the approaches realize the effective suppression of distance ambiguity clutter.Simulation experiments show that the sparse dimensionality reduction approach has a better clutter suppression effect than the JDL dimensionality reduction approach.