Propagation analysis and modeling is critical for radio systems design, but remains a challenge for most through-vegetation situations, including forests. Transmission through such inhomogeneous mixed media is complicated by the many different propagation mechanisms and the complexity of the randomness. This means that accurate, purely physics-based analysis is unlikely to be practical (conveniently computed), and similarly, that practical, purely random modeling is unlikely to be accurate. Through-vegetation propagation models, including the standard radiative energy transfer (RET), are not very accurate in the sense that the uncertainty can be tens of dB, and this seems to be an accepted limitation for vegetation. A simpler propagation model, which maintains or improves accuracy, but keeps a reasonable association with the physics, would be insightful. This paper discusses such a model. It comprises two parallel transmission mechanisms: direct transmission through a succession of trees, which is modeled by a simple linear transmission line; and transmission across the forest top, which is modeled by simplified multiple-edge diffraction. The model is examined using recently-published experiments over a long path-length. It is demonstrated that this two-mechanism model can provide an accurate fit to the dual-slope profile of through-forest propagation over a long distance which is not possible with the RET model.

中文翻译：

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简化森林传播建模


传播分析和建模对于无线电系统设计至关重要，但对于大多数植被情况（包括森林）来说仍然是一个挑战。由于许多不同的传播机制和随机性的复杂性，通过这种不均匀混合介质的传输变得复杂。这意味着准确的、纯粹基于物理的分析不太可能是实用的（方便计算），同样，实用的、纯粹的随机建模也不太可能是准确的。穿过植被的传播模型，包括标准辐射能量传输 (RET)，在不确定性可能达到数十 dB 的意义上并不是很准确，这似乎是植被的一个公认的限制。一个更简单的传播模型，可以保持或提高准确性，但与物理保持合理的关联，将是富有洞察力的。本文讨论了这样一个模型。它包括两种并行传输机制：通过一系列树直接传输，由简单的线性传输线建模；以及穿过森林顶部的传输，这是通过简化的多边缘衍射建模的。使用最近发表的长路径长度实验对该模型进行了检查。事实证明，这种双机制模型可以精确拟合长距离穿越森林传播的双坡剖面，这是 RET 模型不可能实现的。