Monopulse Imaging

Synthetic Aperture Radar and Inverse Synthetic Aperture Radar are two widely used technologies of imaging radar. However, the former one has no capability of forward looking imaging with high resolution, while the latter one relies on the rotation in target's movement. Thus, the application of them is restricted. The technology of monopulse has important value in application to the field of Radar detecting, for the advantages, such as high accuracy of angle measurement, high rate of data acquisition, and the capability of anti-disturbing and forward looking imaging.Starting from the principle of monopulse radar, the thesis analyzes the partition of high resolution range based on the technology of pulse compression, and the angle measurement of monopulse with amplitude-comparison. With simulation, the effect of high resolution and "sum and difference" antenna of monopulse with its performance of angle measurement are analyzed.Although the problem of angle glint occurs in angle measurement of monopulse, it reflects the cross distribution of targets to a certain extent. Based on this point, the thesis sets up the monopulse imaging system model with scanning. And an imaging algorithm of scanning monopulse is proposed, with the idea of doing the imaging processing, using the movement of centers of scatter points because of the scanning of antenna. Through the simulation of multiple point targets, the good effect on imaging of the algorithm is verified. And, according to the analysis of the partition of high resolution range and angle measurement of monopulse, linear frequency modulation signal with wide bandwidth can enhance the range resolution of imaging; while antenna with narrow beam can enhance the azimuth resolution. These conclusions are both verified in simulation.In the image processing of scanning monopulse, super-resolution algorithm is introduced to enhance the azimuth resolution of monopulse imaging system. HFR (High Frequency Raised) is used to improve the azimuth resolution of image. The idea is to inverse the signal distribution around the antenna using the antenna pattern, due to the smooth effect of receiving antenna, with the equal effect of narrowing bandwidth of the beam. Simulation result shows that the azimuth resolution of image is enhanced effectively by the method.To solve the problem of high side lobe caused by HFR, an improved method of weighting by receiving signal is introduced. Simulation result shows that the algorithm effectively restrains the impact of side lobe on image quality.