A New Analytical Model to Study the Ionospheric Effects on VHF/UHF Wideband SAR Imaging

作者：Wang Cheng^*; Chen Liang; Liu Lu

来源：IEEE Transactions on Geoscience and Remote Sensing, 2017, 55(8): 4545-4557.

DOI：10.1109/TGRS.2017.2693396

• Ionospheric effects
• Legendre orthogonal polynomials
• synthetic aperture radar (SAR) imaging degradation

With a view to detecting foliage-obscured/groundobscured targets on a global scale, low frequency (i.e., very high frequency (VHF)/ultrahigh frequency (UHF) band) and wide bandwidth is a trend in future spaceborne synthetic aperture radar (SAR) system design. However, due to the dispersion of ionosphere, VHF/UHF wide bandwidth SAR signals inevitably experience adverse effects. In contrast to narrow bandwidth SAR at VHF/UHF, quadratic and cubic ionospheric phase errors will introduce noticeable effects on future wide-bandwidth SAR systems. Traditional evaluation models based on Taylor series expansion may become inaccurate when an extremely wide bandwidth is considered. With a focus on this this issue, first, the shortcoming of Taylor series expansion of ionospheric phase errors is briefly discussed in this paper. Then, a new analytical model based on Legendre orthogonal polynomials is developed, which is expected to be widely applicable, especially for low-frequency and wide-bandwidth SAR systems. Finally, compared with previous models based on Taylor series expansion, numerical simulations and evaluations show the superiority of the new model.

• 出版日期2017-8
• 单位中国空间技术研究院