Abstract
Wireless sensor networks (WSN) are effective to detect peat and forest fires which can give significant damages in environment and economics. To determine optimal network topology of WSN, one has to know characteristics of electromagnetic wave propagation in forest. In this work, the attenuation constant of waves is evaluated from complex permittivity and basal area of the forest using homogenization technique. It is possible to evaluate the attenuation constant from the measured permittivity of tree trunks and the basal area.