Spaceborne stripmap range sweep SAR: positive terrain tracking by continuous beam scanning in elevation

A Novel Spaceborne Sliding Spotlight Range Sweep Synthetic Aperture Radar: System and Imaging

“…Similar to the discussion for the SS-RSSAR in [17], the CBP of the SSS-RSSAR is assumed to point vertically to the ROI strip as shown in Figure 2, where m denotes the azimuth sampling index and m = 0 denotes the central data acquisition time. The antenna should be continuously manipulated in two dimensions to make sure the ground beam center always moves along the X-axis.…”

“…The SS-RSSAR mode discussed in [17] corresponds to the very case with η = 1. If a traditional constant PI was applied for the SSS-RSSAR, the continuous range-azimuth beam sweeping would lead to slant range variation and inevitably cause the transmission blockage.…”

“…In sum, all these methods have inevitable drawbacks and thus are not the best solutions for the problem of imaging a tilted-with-orbit ROI in high resolutions and with a high data utilization efficiency. To solve this problem, a Spaceborne Stripmap Range Sweep SAR (SS-RSSAR) has been proposed in a previous paper to generate a ROI-matched BIS by continuously sweeping the beam in elevation [17]. However, restricted by its fixed azimuth antenna pointing, the SS-RSSAR can only image a ROI in a stripmap-level azimuth resolution.…”

“…Similar to the SS-RSSAR mode, the SSS-RSSAR's Central Beam Pointing (CBP), which denotes the beam pointing at the central data acquisition time, is arranged to be perpendicular to the BIS for a good balance between the imaging swath and the signal-to-noise ratio [17]. In this case, the SSS-RSSAR is likely to operate with a large squint angle if the ROI is highly squinted with respect to the satellite orbit.…”

“…Due to the perpendicular-to-BIS CBP and its resulted large squint geometry, the echo is to suffer from serious 2D coupling and therefore, the imaging algorithm applied for the SSS-RSSAR should be To solve this problem, a Spaceborne Stripmap Range Sweep SAR (SS-RSSAR) has been proposed in a previous paper to generate a ROI-matched BIS by continuously sweeping the beam in elevation [17]. However, restricted by its fixed azimuth antenna pointing, the SS-RSSAR can only image a ROI in a stripmap-level azimuth resolution.…”