We introduce SodSAR, a fully polarimetric tower-based wide frequency (1–10 GHz) range Synthetic Aperture Radar (SAR) aimed at snow, soil and vegetation studies. The instrument is located in the Arctic Space Centre of the Finnish Meteorological Institute in Sodankylä, Finland. The system is based on a Vector Network Analyzer (VNA)-operated scatterometer mounted on a rail allowing the formation of SAR images, including interferometric pairs separated by a temporal baseline. We present the description of the radar, the applied SAR focusing technique, the radar calibration and measurement stability analysis. Measured stability of the backscattering intensity over a three-month period was observed to be better than 0.5 dB, when measuring a target with a known radar cross section. Deviations of the estimated target range were in the order of a few cm over the same period, indicating also good stability of the measured phase. Interforometric SAR (InSAR) capabilities are also discussed, and as a example, the coherence of subsequent SAR acquisitions over the observed boreal forest stand are analyzed over increasing temporal baselines. The analysis shows good conservation of coherence in particular at L-band, while higher frequencies are susceptible to loss of coherence in particular for dense vegetation. The potential of the instrument for satellite calibration and validation activities is also discussed.

中文翻译：

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基于塔的1–10 GHz SAR系统，用于雪，土壤和植被研究

我们介绍了SodSAR，这是一种基于全极化塔的宽频率（1-10 GHz）范围的合成孔径雷达（SAR），旨在研究雪，土壤和植被。该仪器位于芬兰Sodankylä的芬兰气象研究所的北极空间中心。该系统基于安装在导轨上的矢量网络分析仪（VNA）操作的散射仪，可形成SAR图像，包括由时间基线分隔的干涉对。我们介绍了雷达的描述，SAR聚焦技术的应用，雷达的校准和测量稳定性分析。当测量具有已知雷达横截面的目标时，在三个月内测得的反向散射强度的稳定性优于0.5 dB。估计目标范围在同一时间段内的偏差约为几厘米，这表明被测相位也具有良好的稳定性。还讨论了测距SAR（InSAR）的功能，并举例说明了在不断增加的时间基准上分析了在观察到的北方森林林带上后续SAR采集的一致性。分析表明，特别是在L波段，相干性得到了很好的保护，而较高的频率尤其对于茂密的植被而言，很容易失去相干性。还讨论了该仪器用于卫星校准和验证活动的潜力。在不断增加的时间基准上，分析了随后在观测到的北方森林林区获得的SAR的相关性。分析表明，特别是在L波段，相干性得到了很好的保护，而较高的频率尤其对于茂密的植被而言，很容易失去相干性。还讨论了该仪器用于卫星校准和验证活动的潜力。在不断增加的时间基准上，分析了随后在观测到的北方森林林区获得的SAR的相关性。分析表明，尤其是在L波段，相干性得到了很好的保护，而较高的频率尤其对于茂密的植被而言，很容易失去相干性。还讨论了该仪器用于卫星校准和验证活动的潜力。