Study Of Polarization Information Extraction Technique For Multi-static Radar System

Conventional radar system can get the coordinates, velocity and acceleration of the target, however, these scale parameters of the target can’t satisfy the requirement of modern warfare, so the measurement of the characteristic parameters of the target is becoming the aims of the advanced radar system. Characteristic parameters of the target reflect its own scattering characteristics, including the complex polarization scattering matrix, the distribution of the target scattering centers and the resonant frequency. Among them, polarization information of the target has great potential applications in target detection, enhancement, filtering and identification. Extraction and application of polarization information become the focus of the international radar field.Multi-static radar system has obvious advantages of anti-stealth, low interception, anti-jamming and anti-destroy. The processing technique of polarization information in multi-static radar system can expand the source of information and enhance the awareness of the radar. The purpose of this thesis is to achieve the extraction of polarization information in the conventional multi-static radar system through measuring polarization scattering matrix. The thesis focuses on three issues:the definition and characterization of the bi-static scattering matrix, the measurement system and its inaccuracy, and the solution to delay-Doppler coupling effect in signal processing. The main works are as follows:1. The bi-static measurement model is established to explain the significance and characterization of bi-static scattering matrix. The relationship of coordinate systems and polarization base in bi-static scattering model is obtained. Through polarization base transformation, the Electric field vector of the incident plane wave and scattering plane wave remain a two-dimensional vector, so that the bi-static scattering matrix has the same form of the mono-static scattering matrix.2. Combined with frequency division instantaneous measurement system newly developed, sources of error in model of the radar-environment-target interaction are presented. The frequency response characteristics of the target scattering give a reasonable explanation of the feasibility of the frequency division instantaneous measurement system. The principle, advantages, and disadvantages of this system are discussed in detail.3. A novel architecture of multi-static polarization radar system is proposed with the introduction of the signal processing based on frequency division instantaneous system to measure polarization scattering matrix of the target. Through analyzing the performance of the positive and negative chirp rate of LFM signal and investigating the relationship between the target Doppler frequency and latency of the match filter output, the delay-Doppler coupling effect in the conventional radar is eliminated using the contrary features of delay-Doppler coupling effect in dealing with LFM signals which have positive and negative chirp rate.