PATH-LOSS PREDICTION OF RADIO WAVE PROPAGATION IN AN ORCHARD BY USING MODIFIED UTD METHOD

In this paper, the proposed theoretical path-loss prediction procedure and measured results of radio wave propagation in an orchard environment are presented. The path-loss prediction of wireless sensor network (WSN) in a durian (Durio zibethinus Murray) orchard is chosen to be an example of this study. The three-dimensional (3-D) modified uniform geometrical theory of diffraction (UTD) for curved impedance surface and the complex source point (CSP) technique for source modeling are employed for theoretical path-loss prediction in this paper. The orchard scenario is modeled using canonical geometries of UTD, such as a dielectric flat surface and cylindrical structures with an impedance surface to respectively represent ground and trees. Moreover, since the wireless sensor node is attached to the outside peel of a hanging durian fruit, the fruit partially acts as a wireless sensor node. Therefore, to obtain greater accuracy in the source radiation pattern, the Gaussian beam (GB) expansion via the CSP technique is used for source modeling. The path loss prediction from the proposed numerical procedure and the measured results are in good agreement. The proposed numerical procedure to calculate the path loss from actual scenario of the orchard is useful for network planning such as the pre-harvesting WSN system and other orchard scenarios.