This work describes the path loss of radio propagation for wireless sensor network in the outdoor fruit orchard which is one of the common agriculture environments. The measurement was conducted in the jackfruit orchard in the 2.45 GHz band. Unlike other studies conducted in the fruit orchard environments, the variation of path loss over the relative angles between the plant rows and the line-of-sight direction from the transmitter to the receiver is identified. The equivalent vegetation obstruction model is proposed as the function of the equivalent number of trees along the line-of-sight to better represent the angular path loss variation. This leads to the proposal of the path loss prediction approach at any point in the fruit orchard by using a few measurement efforts. This work also introduces the Monte Carlo simulation using the numerical electromagnetic scattering computation called hybrid T-matrix method to evaluate the relative angular vegetation loss of a single tree that is used as the input to determine the equivalent number of trees. The evaluation results suggest that it can further reduce the measurement workload required for the proposed path loss prediction approach.
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