Research on Alternating Bistatic Mode of Spaceborne Dual-Antenna InSAR System

Spaceborne Dual-Antenna InSAR system has an antenna arm protruding from the satellite. The first (inboard) transmitting and receiving antenna is placed in the shuttle cargo bay while the second (outboard) antenna is installed the other end. The antenna arm is used to form an interferometric baseline. Synthetic aperture radar (SAR) interferometry is achieved by using antennas at both ends of antenna arm transmitting and receiving signals. However, in practical applications (such as the SRTM system in the United States), the length of the antenna arm is limited, and the lack of baseline length results in a low height measurement sensitivity of the InSAR system, which seriously affects the performance of the measurement. In this paper, the alternating bistatic mode which was proposed for TanDEM-X system is applied in the dual-Antenna InSAR system. It is theoretically deduced that the equivalent interferometric baseline (antenna arm) is doubled, although it will lose more coherent than bistatic mode, the measured performance will increase by half. The experiment results verify that it is meaningful to improve the height measurement performance of dual-antenna InSAR system.