A Non-Uniform-Angular-Rate Beam-Scan Method for Airborne TOPS Mode

Abstract

TOPS (Terrain Observation by Progressive Scans) mode can achieve large scene coverage through the beam-scan in a uniform-angular-rate form; when the scanning angle is large, the variation of azimuth theoretical resolution with the scanning angle cannot be ignored. Aiming at airborne SAR (Synthetic Aperture Radar) system, the Doppler characteristic of azimuthal echo of the TOPS mode with large scanning angle is analyzed, and a non-uniform-angular-rate beam-scan method is proposed. By adjusting the angular rate of the beam-scan in a real-time form, we can achieve a consistent azimuth theoretical resolution for the targets at different azimuth location. The simulation results show that the proposed method can alleviate the azimuth resolution inconsistency of about 0.4 m when the azimuth theoretical resolution is 5 m.