粗糙海面建模及其在蒸发波导传播中的应用研究

海上蒸发波导微波超视距电波传播对舰载雷达的运行具有重要的影响. 本文基于粗糙海面电波散射特征和海面高度分布概率密度函数，提出了一种考虑海面遮蔽影响的海上电波传播计算方法，并与两种不包含遮蔽影响的粗糙海面建模的计算结果进行了模拟和试验对比. 计算结果为:1）随着计算频率和风速的增大，不同粗糙海面处理方法的计算结果差异增大，对应位置的路径损耗差异可达10 dB；2）基于试验数据的对比初步显示采用考虑遮蔽影响改进的抛物方程模型预测的路径损耗精度相对较高，粗糙海面对电波的遮蔽效应是蒸发波导传播损耗计算中的一个重要因素；3）试验结果为不稳定大气时采用NPS蒸发波导模型、稳定大气时采用PJ蒸发波导模型预测大气折射率剖面，所预测的路径损耗要优于采用单一蒸发波导模型的结果. 本文所得结果对海上电波传播计算和大气波导的反演等具有参考价值.

Modeling through sea surface and its application in the evaporation duct propagation

Ship radar is affected by the evaporation duct microwave transhorizon propagation over an ocean surface. Based on the radio wave scattered by a rough sea surface and sea surface height probability density function, a new radio wave propagation method is presented, which incorporates the shadowing effect by the wave elevations. In addition, it is compared with two other methods which do not consider shadowing using the modeling and propagation experiment data. The results indicate: 1) The modeling results show that the path losses are different as the computing frequency and wind speed increase, the losses of difference roughness surface handling methods can exceed 10 dB at the same location; 2) It is an important factor in evaporation duct radio propagation that account for the physical mechanism of shadowing from the roughness sea surface. And the effectiveness of this method is preliminarily proved by marine transmission test; 3) Using the experimental data, the results show that the evaporation duct can be better diagnosed using different evaporation duct model at difference atmospheric stability, when the air-sea temperature difference is positive, the PJ evaporation duct is recommended, otherwise, the NPS model is better. The results are useful for radio wave propagation and the inversion of atmospheric duct over the sea.