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P-band ultra-wideband bistatic synthetic aperture radar (UWB BSAR) has the well capability of the foliage penetrating, high-resolution imaging and adding the scattered information, which is potential of detecting the concealed target. However, the P-band UWB BSAR raw data is of the huge amount, big spatial-variance, significant range azimuth coupling and complicated motion error, which increases the difficulty of the efficient and precise reconstruction. In this paper, we propose a reconstruction strategy for the P-band UWB BSAR raw data including the motion errors, which can solve the above problems with the high-efficiency and high-precision. This method requires the local beamforming from the raw data as an intermediate processing in the slant range plane instead of ground plane, which can be exactly referenced to the tracks of the transmitter and receiver considering platform altitudes. And, it derives the requirement for selecting the subapertures and subimages by analyzing the bistatic range error considering the motion errors, as well as sampling requirement of the beam for the subimages, which offers a near-optimum tradeoff between the precision and efficiency. Simulated and measured results show that the proposed strategy is effective, and can achieve the near optimal performance with the low computational complexity. INDEX TERMS Bistatic synthetic aperture radar (BSAR), fast factorized backprojection (FFBP), high-efficiency and high-precision reconstruction, motion errors, P-band ultra-wideband.

The coastline detection is one of the main applications of the Gaofen-3 satellite in the ocean field. However, the capability of Gaofen-3 SAR image in coastline detection has not yet been validated. In this paper, two Gaofen-3 SAR images, acquired in 2016, were used to extract the coastlines of the regions of Bohai and Taihu in China, respectively. The classical Fuzzy C-means (FCM) method was used in the coastline detection, but had been improved by combining the Wavelet decomposition algorithm to better suppress the inherent speckle noises of SAR image. Coastline detection results obtained from two Sentinel-1 SAR images acquired on the same regions were compared with those of the Gaofen-3 images. By using the manually delineated coastlines as the standards in the qualitative evaluations, improvements of about 12.0%, 8.3%, 23.8%, and 9.4% can be achieved by the improved FCM method with respect to the indicators of mean, RMSE, PGSD, and P90%, respectively; demonstrating that the Gaofen-3 data is superior to the Sentinel-1 data in the detection of coastline.