Abstract
For future ultrahigh resolution spaceborne synthetic aperture radar (SAR), it requires the antenna beam capable of large angle scanning in azimuth to increase the azimuth bandwidth and to improve the resolution consequently. To achieve this goal, this paper proposes for the first time a complete implementation scheme based on three-axis attitude maneuvering of satellite platform. Starting from the determination of rotation center, we will deduce the variation of Euler angles during the whole imaging period. Compared with two-dimensional electronical beam-sweeping approach used in phased-array antenna, the most notable advantage of our approach is that it can guarantee azimuth Doppler frequency barely vary along the range line at any azimuth squint angle, which enables the effective decoupling of the signal in azimuth from that in range. Taking advantage of this characteristic, the processing efficiency of high resolution SAR imaging could then be improved to a great extent. Simulation results are presented to verify its effectiveness as well as superiority compared to electronical beam-sweeping.
Highlights
As an active microwave imaging sensor, spaceborne synthetic aperture radar (SAR) has all-day and all-weather imaging capability, making it a very effective and efficient tool in both military and civilian Earth observation applications [1]-[5]
SAR imaging, a large aperture antenna has been selected to increase the antenna gain and signal-to-noise ratio (SNR). This is the reason that the antenna beamwidth is smaller than that of conventional SAR, which makes it necessary to employ sliding spotlight mode and perform beam-steering in the azimuth dimension
It can be clearly observed that 1 becomes 90° when the orbital time ta is in the immediate vicinity of 60 s. Tc can be precisely determined via interpolation
Summary
As an active microwave imaging sensor, spaceborne synthetic aperture radar (SAR) has all-day and all-weather imaging capability, making it a very effective and efficient tool in both military and civilian Earth observation applications [1]-[5]. Its two dimensional echoes will be more and more tightly coupled when the azimuth squint angle becomes gradually larger, leading to SAR image processing increasingly complex To deal with this problem, we propose a novel scheme of attitude maneuvering to realize beam scanning in azimuth. Our scheme ensures that the antenna beam always points to the rotation center by controlling the Z-axis of antenna beam; on the other hand, it minimizes the Doppler frequency variation at any azimuth squint angle by adjusting the X- and Y-axis simultaneously In this way, echoes can be expressed as the product of signal in azimuth and signal in range, indicating the batch processing can be implemented in one dimension after the other so as to improve the efficiency significantly.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
