Ray Tracing and Applications to an Evaporation Duct Model Based on Data from Oceanographic Buoy Sensors

Abstract The two-dimensional ray tracing method allows an easy and fast modeling of tropospheric propagation in the microwave frequency range. A version of this method that determines ray trajectories, amplitudes and delays of the electromagnetic field, as well as the propagation loss in a two-dimensional inhomogeneous environment will be described. The implemented algorithm may consider generalized maps of modified refractivity (or refractive modulus), including not only the vertical gradients, but also their horizontal variations along the path between transmitter and receiver. Next, the present paper will discuss the results from the application of a model of evaporation duct height to data from instruments installed in sea buoys located along the Brazilian coast. Finally, the results from the application of the ray-tracing model to evaporation ducts will be presented, to analyze the propagation of microwave signals in the maritime environment. These results will also be compared with corresponding ones from the software Advanced Refractive Effects Prediction System 3.6, based on the numerical solution of a parabolic equation.

摘要：二维射线追踪方法可便捷高效地对微波频段内的对流层传播过程进行建模。本文将介绍一种适用于二维非均匀环境的该方法变体，其可求解电磁场的射线轨迹、振幅、时延及传播损耗。所实现的算法可支持广义修正折射率（modified refractivity，又称折射模数）分布图的输入，不仅可纳入垂直梯度项，还可覆盖收发链路沿线的折射率水平变化。随后，本文将探讨将蒸发波导高度模型应用于巴西沿岸海域浮标搭载仪器采集数据的研究结果。最后，将呈现将该射线追踪模型应用于蒸发波导的仿真结果，用于分析微波信号在海洋环境中的传播特性，并将所得结果与基于抛物方程数值解法的高级折射效应预测系统3.6（Advanced Refractive Effects Prediction System 3.6）的对应结果进行对比。