Relating Polaization Phase Difference of SAR Signals to Scene Properties
Relating Polaization Phase Difference of SAR Signals to Scene Properties
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DOI：
10.1109/tgrs.1987.289784
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发表时间：
1987
影响因子：
8.2
通讯作者：
F. Ulaby;D. Held;Myron Donson;K. Mcdonald;T. A. Senior
中科院分区：
文献类型：
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作者：
F. Ulaby;D. Held;Myron Donson;K. Mcdonald;T. A. Senior
本文研究了在伊利诺伊州的一个农业试验场的L波段SAR记录的HH偏振和VV偏振后向散射信号之间的相位差AO的统计行为。为大约200块农田生成了偏振相位差分布图，这些农田的地面信息是结合合成孔径雷达使命获取的。在绝大多数情况下，AX分布是对称的，并且具有以偏差的平均值为中心的单个主瓣。然而，对于裸土、切割的植被、苜蓿、大豆和三叶草，发现平均AX接近零度，而对于玉米田，观察到不同的模式;平均偏差为0。随着入射角θ的增加而增加，从θ = 150 °（图像的近距离）处的约零增加到θ = 35°处的约140°。对这种变化提出的解释是，玉米冠层，其大部分的质量包含在其垂直秸秆，像一个单轴晶体的特点是不同的传播速度的波与水平和垂直偏振。因此，假设所观察到的后向散射是由传播延迟、土壤表面的前向散射和秸秆的镜面双站反射的组合所贡献的。基于这一假设的模型计算被认为是在一般协议的阶段观察。
This paper examines the statistical behavior of the phase difference AO between the HH-polarized and VV-polarized backscattered signals recorded by an L-band SAR over an agricultural test site in Illinois. Polarization-phase difference (¿¿) distributions were generated for about 200 agricultural fields for which ground information had been acquired in conjunction with the SAR mission. For the over-whelming majority of cases, the AX distribution is symmetrical and has a single major lobe centered at the mean value of the disstribution ¿¿ Whereas the mean AX was found to be close to zero degrees for bare soil, cut vegetation, alfalfa, soybeans, and clover, a different pattern was observed for the corn fields; the mean ¿¿ increased with increasing incidence angle 0 from about zero at 0 = 150 (near-range of the image) to about 140° at 0 = 35°. The explanation proposed for this variation is that the corn canopy, most of whose mass is contained in its vertical stalks, acts like a uniaxial crystal characterized by different velocities of propogation for waves with horizontal and vertical polarization. Thus, it is hypothesized that the observed backscatter is contributed by a combination of propagation delay, forward scatter by the soil surface, and specular bistatic reflection by the stalks. Model calculations based on this assumption were found to be in general agreement with the phase observations.