A Discrete RET Model for Millimeter-Wave Propagation Through Vegetation

A modified discrete radiative energy transfer (dRET) model has been developed envisaging to overcome some of the limitations found in the original dRET formulation, namely in terms of angular resolution, oblique and nonuniform incidence, and antenna patterns. In addition, the discretized squared nature of the dRET model can lead to some amount of staircase error. Hence, this paper also proposes an input parameter scaling model, enabling the characterization of tree cells with reduced size. The performance of the modified dRET model is assessed not only against the current ITU-R P.833-8 recommendation for propagation in vegetation but also against directional spectra measurements conducted in an outdoor inhomogeneous forest at 20 and 62.4 GHz.