Polarized inverse synthetic aperture radar(Pol-ISAR)is capable of all-weather,all-day and high-reso-lution imaging observation of targets,which is an important means of acquiring information about space targets.Howe-ver,the radio wave propagation effect under complex atmospheric environment may have a significant impact on the ima-ging results.The ISAR imaging model of fully polarized radar under complex rainfall conditions is established.The pola-rized electromagnetic wave amplitude attenuation and phase error caused by the propagation effect under rainfall environ-ment are analyzed.A method to calibrate the propagation effect on ISAR imaging is proposed,which provides important support for the fusion imaging of the multipolar channels.The experimental results verify the correctness of the ISAR ima-ging model and the effectiveness of the propagation effect calibration method under complex rainfall conditions.
In the synthetic aperture radar(SAR)imaging system of high-speed maneuvering platform,the existing design methods of pulse repetition frequency(PRF)have some shortcomings including that the lower bound for the PRF calculated based on the azimuth signal bandwidth is too high,and the factor of radar's duty ratio is neglected.In view of the above problems,firstly,a set of constraint equations that related to PRF and duty ratio are derived to avoid the fac-tors such as transmitting pulse interference,echo interference directly below the platform and range ambiguity.Then,a new design method for the lower bound of PRF in the case of range sectioned SAR imaging is proposed.The simulation results show that the proposed method can achieve a smaller PRF lower limit when highly squinted spotlight SAR imag-ing seeker moves at a high speed,which effectively expands the range of PRF selection and can better meet the need of practical engineering applications.
To address the problem that multiple-input multiple-output(MIMO)frequency modulated continuous wave(FMCW)radar is difficult to accurately detect multiple people's vital signs in indoor environments,a multi-target vital signs detection method based on MIMO-FMCW radar is proposed in the paper.Firstly,the range fast Fourier trans-form(FFT)and Capon angle estimation are performed on the IF signal to obtain the distance angle map.Accordingly,the distance and angle information of each target is determined by using the two-dimensional constant false alarm detec-tion technique(2D-CFAR)and density-based clustering of applications with noise(DBSCAN)algorithm.Then,the digi-tal beamforming is performed by the linear constraint minimum variation(LCMV)criterion to obtain the slow time sig-nal for each target.In particular,the arctangent demodulation is used to achieve the extraction of phase signal.Finally,the harmonic discrimination criterion is adopted to obtain the respiration rate and heart rate for each target.The experi-mental results show that the proposed method can realize the detection accuracy of respiration rate and heart rate with an average relative error of less than 10%.
A passive bistatic radar system for the detection of moving targets at sea is designed in this paper. Through the continuous acquisition of non-cooperative radar direct wave and echo data, pulse compression, incoherent integration, MTI moving target processing, adaptive constant false alarm detection, and finally realize the detection of maritime targets. In this paper, the process of the proposed method is explained in detail, and then the field experiment is carried out. The experiment obtained clearly range-azimuth display image and PPI display image. Preliminary results of field experiments show that the system can successfully detect targets at sea.
In this paper, a high frequency electromagnetic scattering acceleration method for targets is proposed, which combines CPU multi-core parallel technology, GPU hardware acceleration technology and KD-Tree traversal technology. The high frequency electromagnetic scattering model of complex targets including ships with cavity, angular reflector arrays and ships is established, which can meet the needs of rapid evaluation of large targets. In this paper, a fast prediction method for multiple scattering range image position is proposed. By combining multiple scattering ray diversity with ray path phase prediction theory, the multiple scattering equivalent apparent position of the center is deduced rapidly, and the multipath scattering mechanism and action process of the target containing cavity are revealed. Through the simulation and analysis of ship target, the mapping relationship between the strong scattering contribution formed by multiple scattering of large target and its specific geometric structure is established.
