Where, hT and hR are the transmitting and receiving antenna heights over the ground in meters respectively. It is assumed that df is larger then hT and hR,. 1 and 2 are the phase differences between the direct and ground-reflected rays and the direct and tree-canopy reflected rays respectively. For 1 , hT = hR = h2; and for 2, hT = hR = h1 (see figure 1).
By incorporating the foliage-induced excess loss for the radio-wave propagation through the forest medium, the following
models were obtained [6]: The path loss (PL) model due to the tree-canopy reflections (or tree-canopy and ground reflections) is given by: