Research On Airborne Bistatic Polarization Radar System

The wide application of digital array technology in radar systems has provided a realistic basis for airborne bistatic polarization radar system engineering.Compared with monostatic arrays,the bistatic configuration combines the advantages of airborne bistatic radar and polarization sensitive arrays in solving problems associated with complex electromagnetic environments,heterogeneous clutter suppression,and low speed target detection,enabling the acquisition of space,time,frequency,polarization,and multidimensional information.Here,we describe the airborne bistatic polarization radar system and the system’s design;we focus on active noise interference suppression,active interference identification,airborne bistatic polarization clutter suppression,and target detection.The following is a summary of the system’s features,specifications,and achievements.A new airborne bistatic polarization radar system,based on the airborne bistatic radar and polarization-sensitive array,is presented that solves the current problems facing current airborne radar in terms of system architecture,combat mode,and collaborative detection.To achieve high-speed,efficient transmission of airborne bistatic broadband data,a communications method using radar antenna arrays is proposed that considers normal radar operation and the efficient transmission of broadband data.The radar working mode is closely coupled with broadband communication to make full use of the system’s resources.To improve the active anti-interference capability of the airborne bistatic radar system,an intelligent neural-network closed-loop architecture is proposed to preset the transmitting beam and receiving beam of the radar,and reduce the risk of launch interception and effectively suppresses main-lobe interference,through autonomous learning of the external electromagnetic environment.To manage active noise interference suppression of the main-lobe and side-lobe,an airborne bistatic hierarchical interference suppression method is applied,in which the airspace degree of freedom of the monostatic radar is used to suppress side-lobe interference;this is followed by elimination of the main-lobe interference with the bistatic radar.A retreat method is proposed to manage simultaneous overlapping multiple main-lobe interference;in this method,multiple main-lobe interferences are retracted and suppressed in a sequential manner until the interferences have been eliminated.For active deceptive interference,identification based on the spatial positioning of airborne bistatic radar is proposed,in which the recognition of real and false target spatial positions is improved by acquisition of three-dimensional information.To manage airborne bistatic polarization anti-interference,a bistatic polarization grading method is proposed to eliminate main-lobe and side-lobe interferences.First,the spatial degree of the monostatic radar is used to suppress side-lobe interference.The polarization degree of the bistatic radar is then used to suppress main-lobe interference,thus achieving suppression of multiple main-lobes and side-lobes.Interference space steering is corrected to further improve the effects of main-lobe interference suppression before main-lobe interference elimination.To manage active deceptive interference,a method for the identification of active false targets by airborne bistatic polarization is proposed,based on the comprehensive application of airborne dual base and polarization information.First,the polarization features of real and false targets are extracted.Then,the polarization characteristic quantities are compared according to the polarization features of the real target polarization scattering characteristics.Dissimilarities are used to ultimately identify real and false targets.Airborne bistatic clutter suppression is achieved by combining the advantages of sparse recovery in sample selection and full polarization processing in low-speed clutter regions.The method shows enhanced suppression of airborne bistatic clutter,particularly in low-speed areas,which enables improved target detection in these regions.For the typical application scenarios of airborne bistatic polarization radar,a method for full polarization target detection and non-coherent accumulation is proposed,based on the two modes of "T/R-T/R" and "T/R-R".This method first performs full polarization target detection of the primary and auxiliary radar under the first low threshold to reduce the clutter dimensions.A block matrix is then applied to the clutter and noise covariance matrix,to reduce the operation amount and improve the operational efficiency.The results of the primary and auxiliary radar of the airborne bistatic radar are accumulated to further improve the target signal-to-noise ratio and control for false alarms via the second threshold,thus achieving optimal detection of the airborne bistatic target.