Clutter height variation and its effect on frequency dependence of radio path loss

Propagation of radio signals from a base above variable height clutter, such as buildings and trees, to a mobile immersed in clutter is treated theoretically. It is found that the frequency-dependent scattering loss at the upper boundary of the clutter re-produces the frequency dependence reported in empirical models. Closed form expressions are derived for path gain in both urban and heavily foliated environments. The resulting predictions are in close agreement with widely accepted models and empirical results, including both range and frequency dependence. It is found that describing path loss dependence on frequency as a power law has limitations as the exponent varies both with frequency and base height above clutter. Compact expressions obtained here may be used instead.