Simulation of HF propagation through a grid of conducting rods with application to forest modeling

Designing HF communication systems to work in forested environments motivates a desire to understand the forest as a medium for radio wave propagation. At HF frequencies the forest is highly anisotropic because the most significant scatterers are vertical tree trunks. So, a reasonable first-order model of the forest is a grid of vertical scatterers. Using the Numerical Electromagnetic Code (NEC), a moment-method-based program, a grid of long vertical wires was simulated. Antennas inserted in the grid allow a relative permittivity of the grid as a composite medium to be determined. The length and distribution of the rods and the presence of a realistic ground plane are shown to influence dispersion in the simulated grid.