Research On Radar Anti-interference And Optimization Detection Based On Polarization Diversity Technology

In modern wars,radars are confronted with difficult problems such as penetration in low and very low altitude and target detection in the environment of noise and clutter.With the continuous advancement of radar technology,the new system polarization radar can improve the performance of radar systems by taking advantage of backscattering polarization information.Previous polarization technologies generally use the horizontal and vertical polarization(or left-handed and right-handed circular polarization)due to the restriction of radar polarization states,and the capacity of polarization information processing has not been fully developed.The latest developed polarization radar can transmit arbitrary polarization pulse.Comparing with conventional radar,this polarization radar can select the optimal emission polarization according to the a priori knowledge of the environment,and the performance of the radar can be further enhanced.Radar anti-interference and adaptive optimization detection algorithm based on polarization diversity is studied aiming at some difficulties in anti-interference and detection.The major content includes:symmetric polarization diversity algorithm to restrain angular glint of low-altitude interference which is caused by penetration in low and very low altitude;polarization and waveform optimization detection algorithm in the homogeneous,partially homogeneous and inhomogeneous clutter environment.Taguchi optimization algorithm is introduced in this paper to solve the parameter optimization problem.First,the suppression of angular glint of low-altitude interference caused by penetration in low and very low altitude is studied.By adopting two-point glint model,the angular glint linear deviation is expressed in the formula in which the phase and the amplitude polarization parameters of the antenna are considered.The relationship between the function of the angular glint linear deviations and the polarization parameters is investigated in this paper,and the minimum point is found by Taguchi optimization algorithm.The design of symmetric polarization diversity is symmetric relative to minimum point to ensure the angular glint linear deviation each diversity has a certain degree of inhibition.Finally,the angular glint linear deviations are decreased substantially by symmetric polarization diversity offset.Experiment results indicate that the proposed method gives higher performance than other methods in restraining the angle glint of low-altitude interference.Second,the detection problems of two detectors,i.e.Generalized Likelihood Ratio Test(GLRT)and Adaptive Matched Filter(AMF)are studied in the homogeneous environment.Firstly,the monotonicities of the detection performance with one parameter for the two detectors are studied.The parameter with polarization parameters is equivalently decomposed to enhance detection efficiency,while it is maintaining high detection performance.And the proposed polarization decomposition makes the multiplication number of the algorithm from a square increasing to a linear increasing as the parameters increase.The study also found that the parameter is closely related to the waveform parameters and polarization information.Therefore,two approaches for the transmitted waveform design are proposed.Secondly,an adaptive polarization diversity and waveform design optimization algorithm based on GLRT and AMF is proposed and it makes this optimization detection issue transform into a multiple parameters optimization problem.Thirdly,the Taguchi optimization algorithm is used to solve this optimization problem.Experiment results indicate that the further improvement both on detection efficiency and performance can be achieved by the proposed algorithms than others in the homogeneous environment.Third,we consider Adaptive Subspace Detector(ASD).Rao and Wald tests for polarization optimization detection in partially homogeneous environment.Firstly,the monotonicities of detection probability of the two detectors are studied.Secondly,a polarization optimization detection algorithm to enhance the detection performance is proposed.Thirdly,the polarization decomposition algorithm and the adptive polarization diversity and waveform design optimization algorithm above are used in ASD,Rao Test and Wald Test for optimization detection.The numerical simulations illustrate the improvement in the detection performance of the proposed optimization algorithm.Fourth,the problem of detecting targets in inhomogeneous clutter is addressed by exploiting adaptive polarization and waveform diversity optimization design jointly.Firstly,we introduce a signal detection model included inhomogeneous clutter.And the logarithmic generalized likelihood ratio test(GLRT)detector is proposed whose decision-making capability is based only on the data collected from the range cell under test,without resorting to secondary data or prior knowledge of the target and clutter.This feature makes it robust against inhomogeneous and nonstationary clutter.Secondly,a deep study of a polarimetric optimization detection algorithm is conducted in this paper.Thirdly,the adptive polarization diversity and waveform design optimization algorithm above is used in logarithmic GLRT to further improve the target-detection performance.Experiment results indicate that the more significant improvement on detection performance can be achieved by the proposed method than other algorithms.