高仰角对流层散射传播损耗的改进预测方法

鉴于ITU-R P.617建议只可用来计算低仰角而不适合于高仰角情形下的对流层散射传播损耗，提出了一种适用于高仰角对流层散射传播损耗的改进预测方法.分析了不适用于高仰角情形的原因，发现散射体离收发连线的高度H可能小于离地高度h，而通常的物理含义下H > h.因此根据散射几何模型，替换了原有的散射体高度表达式，在近似条件下令两个散射体高度相等，将新的散射体高度表达式代入计算.链路预测结果表明:改进的简单预测方法极大地改善了原有预测结果，更加接近实验结果，且与适合于高仰角的复杂美国国家标准局（National Bureau of Standards，NBS）方法预测结果基本一致.

An improved prediction method of the troposcatter propagation loss with high elevation

Usually we use ITU-R P.617 recommendation to compute the troposcatter propagation loss of low scatter angle case,however,it is not fit for the high scatter angle case.We propose an improved method for high scatter angle case in this paper,and analyze the reason why it is not fit for the high scatter angle case.We find that the height of the common volume above the line of transmitter and receiver called H maybe smaller than the height above the ground called h,but from the physical meaning,H must be larger than h.So according to the geometry model,we replace thc original expression of H,and in an approximate condition we suppose the two heights are equal.If we substitute the new expression into the link prediction,we find that it is improved well compared to the original results and closer to the experimental results.The proposed method is also agreed well with complex U.S.National Bureau of standards (NBS) method which is used for both low and high elevation.