The Character Analysis Of Mobile Bistatic(Multistatic) Radar Echo

In the last several decades, with the development of electronic warfare, electronic jamming, ARM, over-low altitude penetration and stealth weapons have become the main threats of radar. Because bistatic(multistatic) radar has more advantages to overcome the four kinds of threats than traditional monostatic radar, people begin to pay more attention to this kind of radar. The mobile bistatic(multistatic) radar of this paper is a combination of bistatic(multistatic) radar and shipborne high-frequency ground wave over-the-horizon(OTH) radar. This kind of radar not only has the advantages of bistatic(multistatic) radar, but also has the character of OTH. So it has a good foreground. Of course, the mobile bistatic(multistatic) system is very complex. In this complex system, the analysis to the echo of target and ocean wave is very important to the detection and information extraction of target.The multistatic radar in this paper is a networking bistatic system, so this paper mainly researches the bistatic system. This paper firstly establishes a general coordinate system, so we can get the accurate expression of the position of radars and target, and the change of ranges and angles between them. And then this paper discusses range relationship and Doppler frequency of bistatic system.This paper also analyses the waveform and parameter selection of linear frequency modulated interrupted continuous wave(LFMICW). After getting the echo delay of target, this paper derives the expression of target echo in radio frequency and intermediate frequency, and then analyses the meaning of phases in the expression and the relationship to the motion of target and radars. Also this paper discusses the feasibility of two-dimensional FFT to the information extraction of target in this situation. To the disadvantage of two-dimensional FFT in precision and resolution for range measurement, after compensating the range-Doppler factor, this paper uses chip-z transform to improve the precision, and uses the sparse representation to improve the resolution. For the error of velocity measurement because of the Doppler frequency broadening when target is very close to the radar, it uses time-frequency analysis to improve the precision, and analyses the method to get the complete velocity in multistatic situation.Finally it analyses the first order sea clutter when the radar platforms are fixed and mobile, include the mechanism of first-order bistatic Bragg scattering, the character of its Doppler frequency and RCS, and then analyses the shape and broadening of its Doppler spectrum with narrow beam and omni-directional antenna. The pilot study about how to get the accurate range of target when the Doppler frequency of first-order sea clutter and target echo separates, by filtering the sea clutter in columns of two-dimensional FFT matrix, is discussed.