Abstract
The paper proposes a new method for measuring the azimuth pointing of spaceborne synthetic aperture radar (SAR) antenna beams based on the ground receiver, which can receive and record complex sampling data of the pulse signals transmitted from the spaceborne SAR. The center of the antenna pattern is extracted from the complex sampling data amplitude envelope to obtain the time when the beam main lobe center irradiates the ground receiver, and the range migration information is extracted from the complex sampling data to obtain the time when the satellite is over the top of the ground receiver. The results of Chinese civilian remote sensing GaoFen-3 SAR satellite experiment data processing show that the measurement accuracy of this method is better than 0.002°, which can be applied to the accurate measurement of azimuth pointing of various low Earth orbit (LEO) SAR antenna beams.
Highlights
Spaceborne synthetic aperture radar (SAR) antenna pattern modulation is the main error source affecting the SAR image radiation precision
We propose a high-precision measurement technique for the azimuth direction of the SAR antenna beam based on the ground receivers, which solves the above problems while achieving an accuracy of 0.002◦
According to the working mechanism of spaceborne SAR, while the satellite is in work, the chirp signal is transmitted at a fixed pulse repetition frequency (PRF) while the ground receiver receives the SAR chirp signal
Summary
Spaceborne synthetic aperture radar (SAR) antenna pattern modulation is the main error source affecting the SAR image radiation precision. The on-orbit measurement of the antenna pattern of the spaceborne SAR is divided into two aspects: the shape of the antenna pattern measurement and antenna beam pointing measurement. The DLR designed and implemented a calibration method for TerraSAR-X to measure the antenna beam pointing via transmitting a special kind of antenna beam with a notch pattern, and the accuracy in range direction was better than 0.008◦ [16]. The beam pointing in the azimuth direction could be determined likewise by notch patterns operated in the azimuth direction and measured by deployed ground receivers, with accuracy better than the required 0.002◦ [17]. We propose a high-precision measurement technique for the azimuth direction of the SAR antenna beam based on the ground receivers, which solves the above problems while achieving an accuracy of 0.002◦.
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