An initial critical summary of models for predicting the attenuation of radio waves by trees

Abstract : This report is a review of models and data that can be used to predict the increase in attenuation due to trees and underbrush that are located between a radio transmitter and receiver. Applications in the 3 MHz to 95 GHz band are addressed with emphasis placed on the 200 to 9200 MHz range. It is shown that the conventional technique for predicting the loss caused by propagation through a small grove of trees is often substantially in error. An improved empirical model is developed to mitigate the problem; a physical justification for the model is presented. (Author)