Design Of Broadband-Polarization Radar Test System

The increasingly complex electromagnetic enviroment pursues the ability of radar to detect targets accurately from a farther distance. Besides, a strong capability of inteligent information processing is necessary. Furthermore, for the sake of correct target recognition and classification, it is hoped to extract as much information of target's physical feature from returns as possible. Full-polarization and high resolution are two important research topics of modern radar. The two techniques describe the target characteristcs from different aspects, which reveals a wide application prospect of their combination. On the one hand, polarization information in echo descibes targets' physical properties such as structure, surface roughness, and material. Therefore, namely a complete description of targets' physical properties can be obtained with polarization information. On the other hand, the technique of high resolution clearly depicts the tiny feature of radar target, which greatly improves the accuracy of targets' polarization description model.Firstly, this paper introduces the basic theory of broadband-polarization radar, including the polarization scattering matrix, polarization measuring system, and one-dimension high resolution imaging algorithm based on the step frequency signal. Then the one-dimension high resolution range profiles(HRRP) of full-polarization data in four channels are obtained in simulation experiment, which reveals the relationship between the polarization scattering matrix and HRRP.Secondly, the structure and parameter design of the broadband-polarization radar test system are introduced. The part of structure design deals with radar receiver and transmitter. And several single modules like transmitting waveform design, mixer, and amplifier are discussed in details. In addition, the parameter design determines radar system parameters such as the transmitted power and receiver sensitivity, dynamic range, and gain, etc.. With repeated modification and adjustment, theoretic factors finally meet the requirement of radar. After that, the broadband-polarization radar test system is verified by Matlab/Simulink. A dual-channel radar receiver is established with afore-designed modules. The full polarization returns can be obtained in two pulse repeated intervals, which can be observed by oscilloscopes placed at key modules. The simulation results validates the correctness of this test system.Finally, two relative algorithms of data processing are introduced. One is the polarization calibration algorithm with Pauli based decomposition. The other is polarization scattering matrix estimation algorithm based on P_ESPRIT. Both of two algorithms are verified by the Simulink simulation data and measured broadband-polarization data, respectively. Experiment results prove the correctness of these data processing algorithms used in the radar test system.