## 1 Introduction  
Wireless sensor networks (WSNs) are emerging as a significant technology with applications in a variety of fields, such as industrial sensing, health monitoring, sports applications, consumer and military applications [1]. With the adequate developments in design and fabrication technologies for ubiquitous wireless connectivity, monitoring of physical and environmental parameters in vegetation environments have been gaining importance in recent years. One of the most important applications of sensing a variety of phenomena such as temperature, relative humidity and smoke in vegetation environments, is for fire detection systems. In [2], the authors show the feasibility of using WSNs for forest fire monitoring. A forest surveillance system for South Korea mountain ranges using sensor networks was designed in [3,4], where the authors present the design and evaluation of a WSN for early detection of forest fires. Another example of forest fire monitoring system based on GPRS and a ZigBee WSN is presented in [5]. WSNs have been also used in a forest environment in [6] for real-time detection of illegal timber logging activities based on sound recognition. However, the proper design of a WSN for use in large space monitoring could be a very challenging process. When designing any wireless network a relevant aspect to be considered is the maximum distance between two nodes that still ensures a reliable wireless connection. This depends on a variety of parameters such as the transmitter power, the receiver sensitivity, the signal propagation environment, the signal frequency and the parameters of the antennas. Especially, in vegetation environments, the appearance of the foliage in the path of the communication link plays a key role on the quality of service (QoS) for wireless communications systems [7, 8, 9, 10]. Discrete scatterers such as randomly distributed leaves, twigs, branches and tree trunks can cause attenuation, scattering, diffraction and absorption of the radiated waves. This severely constrains the design of wireless communication systems in inhomogeneous vegetation environments. The foliage effect on the path loss, shadowing and multipath dispersion has been given considerable attention from the literature. [PERSON] _et al._[7] conducted some empirical foliage loss prediction models for the studies of the isolated foliage effect on a mobile-satellite channel. [PERSON] [8] mainly contributed to the studies with the influence of lines of trees along the streets. An excellent work was performed by [PERSON] _et al._[9] with a semi-empirical modeling of the foliage loss for the implementation of high speed wireless systems. The rapid development of WSNs requires a thorough understanding of the wireless communication channels. The functioning of a WSN is clearly dependent upon having adequate signal levels at the distributed nodes, and thus designing effective WSN requires accurate propagation modelling capabilities for complex environments. Because of that, it is highly important to conduct previous radio propagation analysis when deploying a WSN. Traditionally, empirical methods were used (such as COST-231, Walfish-Bertoni, Okumura Hata, _etc._) [11] for initial coverage estimation. They are time efficient but are less accurate than deterministic methods, which are based on numerical approaches to the resolution of Maxwell's equations. Deterministic methods, such as ray launching and ray tracing (based on geometrical optics) [12] or full-wave simulation techniques (method of moment (MoM), finite difference time domain (FDTD), FITD, _etc._), are precise but are time-consuming to inherent computational complexity. As a midpoint, deterministic methods based on geometrical optics, offer a reasonable trade-off between precision and required calculation time [13,14]. Deterministic modeling has been used in this work to conduct the characterization of the physical channel for radioplanning purposes in a vegetation environment.