TY - JOUR
T1 - A Cascaded Autofocus Method for Earth-Based Radar Moon 3-D Imaging under Multisource Phase Errors Based on Entropy Gradient
AU - Ding, Zegang
AU - Yang, Yuewen
AU - Dong, Zehua
AU - Wang, Zhen
AU - Liu, Peiyao
AU - Zhou, Ziyi
N1 - Publisher Copyright:
© 1980-2012 IEEE.
PY - 2026
Y1 - 2026
N2 - The Moon is Earth's only natural satellite, and observation of the Moon is of great importance in scientific research and engineering applications. Earth-based radar is a powerful approach for Moon observation, and is capable of acquiring a Moon 3-D radar image. However, various nonideal factors lead to intratrack and intertrack phase error, which degrade 3-D imaging quality. To address this issue, this article proposes a novel cascaded autofocus method for Earth-based radar Moon 3-D imaging. The contribution of the article mainly consists of two parts. The first is the comprehensive modeling for complex phase errors, where different types of phase errors are modeled as a polynomial or periodic function of azimuth time. The impact of complex phase errors on Moon 3-D imaging is analyzed. The second is the error estimation and compensation algorithm for multisource complex phase errors that does not rely on strong scatters. This algorithm uses the image energy maximization criterion to truncate the optimal imaging region for autofocus. The analytical iteration format based on the partial derivation of distributed target entropy is given. In addition, the 2-D and 3-D autofocus is performed in cascade to separately estimate errors in the time-domain, which does not rely on a certain coordinate system property. Computer simulations and real data experiments based on an Earth-based radar system are conducted to validate the proposed method.
AB - The Moon is Earth's only natural satellite, and observation of the Moon is of great importance in scientific research and engineering applications. Earth-based radar is a powerful approach for Moon observation, and is capable of acquiring a Moon 3-D radar image. However, various nonideal factors lead to intratrack and intertrack phase error, which degrade 3-D imaging quality. To address this issue, this article proposes a novel cascaded autofocus method for Earth-based radar Moon 3-D imaging. The contribution of the article mainly consists of two parts. The first is the comprehensive modeling for complex phase errors, where different types of phase errors are modeled as a polynomial or periodic function of azimuth time. The impact of complex phase errors on Moon 3-D imaging is analyzed. The second is the error estimation and compensation algorithm for multisource complex phase errors that does not rely on strong scatters. This algorithm uses the image energy maximization criterion to truncate the optimal imaging region for autofocus. The analytical iteration format based on the partial derivation of distributed target entropy is given. In addition, the 2-D and 3-D autofocus is performed in cascade to separately estimate errors in the time-domain, which does not rely on a certain coordinate system property. Computer simulations and real data experiments based on an Earth-based radar system are conducted to validate the proposed method.
KW - Earth-based radar
KW - Moon 3-D imaging
KW - phase error compensation
KW - synthetic aperture radar
KW - time-domain autofocus
UR - https://www.scopus.com/pages/publications/105028387680
U2 - 10.1109/TGRS.2026.3656358
DO - 10.1109/TGRS.2026.3656358
M3 - Article
AN - SCOPUS:105028387680
SN - 0196-2892
VL - 64
JO - IEEE Transactions on Geoscience and Remote Sensing
JF - IEEE Transactions on Geoscience and Remote Sensing
M1 - 5202618
ER -