Modeling forest propagation loss over a vast area is challenging, particularly for the hilly terrain regions where canopy obstacle depth varies with region. To consider such vegetation impact, we present a novel forest cover classification well defined with the line-of-sight (LoS). Furthermore, we incorporated the mobile antenna site elevation angle, which showed significant influence within the target frequencies selected at 182.25 and 203.25 MHz (VHF Band III). We proposed a loss exponent dependent on the elevation angle and the vegetation-visibility classification, which is the basis of the model introduced in this paper. The resulting loss derived using this loss exponent showed a good agreement with the empirically derived loss variations. The proposed method offers easy forest classification approximations with precise determination of signal variation over a wide-ranging forested area.

中文翻译：

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VHF频段III中丘陵林区的损失指数建模

模拟大面积森林传播损失具有挑战性，特别是对于树冠障碍物深度随区域变化的丘陵地形区域。为了考虑这种植被影响，我们提出了一种用视线 (LoS) 明确定义的新型森林覆盖分类。此外，我们纳入了移动天线站点仰角，这在 182.25 和 203.25 MHz（VHF 频段 III）选择的目标频率内显示出显着影响。我们提出了一个依赖于仰角和植被能见度分类的损失指数，这是本文介绍的模型的基础。使用该损失指数得出的最终损失与经验得出的损失变化非常吻合。