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本文研究了湿润土壤的微波辐射特性及微波遥感土壤湿度的方法。首先用终端短路线法测量土壤介电常数和湿度的关系;介电常数的实部和虚部都是随着土壤湿度增加而加大的。用研制的微波辐射率仪测量土壤微波辐射率和湿度的关系。土壤微波辐射率随着湿度加大而降低的。土壤湿度不同引起显著的亮度温度变化。本文还研究了在土壤中微波的衰竭厚度以及土壤中湿度分布对辐射率的影响;土壤表面粗糙度对于辐射率的作用。从原理分析和实验结果表明,微波辐射计是遥感土壤湿度的良好工具,3.2cm波段较8.5mm波段测土壤湿度优越,它不但灵敏度高、穿透深度较深而且受表面粗糙度的影响亦小。
In this paper, the microwave radiation characteristics of wetting soil and microwave remote sensing of soil moisture were studied. First, the relationship between the dielectric constant of soil and the humidity was measured by the terminal short-circuit method. The real and imaginary parts of the dielectric constant increased with the increase of soil moisture. Using the developed microwave radiometer to measure the relationship between soil microwave radiation and humidity. Soil microwave radiation rate decreases with increasing humidity. Different soil moisture causes significant brightness temperature changes. The paper also studied the failure thickness of microwave in soil and the effect of soil moisture distribution on emissivity; the effect of soil surface roughness on emissivity. The principle analysis and experimental results show that the microwave radiometer is a good tool for remote sensing of soil moisture. The measured soil moisture in the 3.2cm band is superior to the 8.5mm band. It not only has high sensitivity, deep penetration depth but also is affected by the surface roughness .