Key technologies for on-orbit azimuth antenna pattern measurement of TH-2 dual satellites

doi:10.11947/j.AGCS.2022.20210373

Abstract

Abstract: On-orbit (inflight) measurement of the antenna pattern of space-borne synthetic aperture radar (SAR) is an indispensable and important procedure for SAR calibration, performance tuning and index test. Usually, in practical on-orbit (inflight) measurement of the SAR antenna pattern, it is separated into the vertical (elevation) and the horizontal (azimuth) directions respectively. The TH-2 satellite set is made up of two satellites to enable bistatic interferometry SAR (InSAR) observation. At the beginning of the on-orbit tests, the two satellites adopted a “following” flying formation in which one satellite flew about 40km away after the other one. In this phase, the two satellites worked independently in SAR observation model to facilitate calibration, tuning and test of the satellites individually. When conducting the azimuth antenna pattern measurement, the collected signals from the two satellites in the ground receiver were overlapped (interleaved) and superposed, leading to the difficulty of measurement with the method designed for only one satellite. Aiming at solving this problem, an efficient and fully automated signal separation method for azimuth antenna pattern measurement is proposed. Based on the modeling and analysis of the sampled signal in the ground receiver, a novel signal separation method based on three main parts: key pulse rising edge extraction, pulse position estimation and pulse amplitude estimation is proposed to realize the separation of the signals from different satellites. After signal separation, the subsequent antenna pattern measurement tasks can be done using the traditional single-satellite method. Experimental results sufficiently show the effectiveness of the proposed method. This method escorted the on-orbit tests of the satellites smoothly, and the test efficiency can be doubled compared with the individual test of each single satellite. The proposed method can be used in the on-orbit tests of similar satellites in the future.

Key words: antenna pattern, azimuth antenna pattern, signal separation, InSAR satellites, on-orbit tests

CLC Number:

P237

GAO Jingkun, WANG Zhilong, CHENG Jiasheng, CONG Lin, FAN Weikang, HU Zhenlong. Key technologies for on-orbit azimuth antenna pattern measurement of TH-2 dual satellites[J]. Acta Geodaetica et Cartographica Sinica, 2022, 51(12): 2470-2480.

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