Interferometric Alignment of Spaceborne Dual-antenna Sar System

In spaceborne dual-antenna (i.e., single-pass mode) interferometric synthetic aperture radar (InSAR) system, the alignment of the master and slave antenna beam is crucial. In order to achieve the best interferometric performance, antenna beams should be coincided with each other between the master and slave. The beam alignment of the first spaceborne dual-antenna InSAR system, the Shuttle Radar Topography Mission (SRTM) with a 60 m deployable mast assembled on the Space Shuttle Endeavour, has been discussed in detail [1]. This can provide some technical reference for the InSAR beam alignment. However, compared with the SRTM beam alignment, the traditional satellite-borne mode of our InSAR system makes a different baseline configuration. Meanwhile, the Attitude and Orbit Determination Avionics (AODA) equipped in the SRTM system, which provides in-flight measurements to support antenna alignment, is absent in our InSAR equipment due to some systemic consideration. Therefore some techniques for real-time attitude measurement of the master and slave antennae are required. In this paper, the alignment system of our InSAR system is described, especially for the satellite-borne baseline configuration and the adjustment of radar beam. Then a three-step alignment scheme, which is composed of coarse alignment, fine alignment and alignment maintenance, is proposed. The technical points for each step are briefly introduced, and an outstanding alignment performance is achieved.