Seong Joo Maeng

한국전자파학회논문지 (The Journal of Korean Institute of Electromagnetic Engineering and Science)

This paper analyzes the performance of the bistatic staring spotlight mode in a low-orbit satellite environment and then compares it with the performance of the monostatic staring spotlight mode. The staring spotlight mode provides high-resolution images by continuously stare at the target via azimuth beam steering. However, monostatic synthetic aperture radar (SAR) systems may not achieve the desired performance in this mode owing to the geometric limitations of performing missions using a single satellite. To overcome these limitations, a bistatic SAR system that uses two satellites is considered in this study. By using two satellites, uncertain ground structures can be handled with flexibility. Moreover, a strategically planned design for a bistatic SAR system can help achieve a wider range and better performance than a monostatic SAR system. By applying this design to the staring spotlight mode, a SAR system that offers both high-resolution images and good performance is proposed.

In this paper, the performances of spaceborne bistatic synthetic aperture radar (SAR) systems are evaluated and compared with those of the conventional monostatic SAR system. Drawing on information on the altitude of satellites and the pulse repetition frequency of the system, the distance between the satellites carrying the transmitter and the receiver is first determined to then obtain the maximum observable width by overlapping the blind ranges. The performances of the bistatic SAR for two satellites at the same altitude moving parallel to each other at the same speed are evaluated, and the results are compared with those obtained from a monostatic SAR system located at left or right end of the baseline. The resolutions, noise equivalent sigma zero, and ambiguities of the bistatic SAR are evaluated based on the windows between blind incident angles of a timing diagram. Subsequently, the most ap-propriate window is determined by comparing the evaluated performances of the bistatic SAR.