Path Loss Characterization at the 1800 and 2100 MHz Frequency Bands in Citrus Plantations

Agriculture 4.0 is revolutionizing crop production by leveraging advanced sensor networks and wireless technologies, with efficiently planned radio communication systems serving as a key component. In this paper, we develop a theoretical model for calculating the propagation path loss in a Line-of-Sight (LoS) context in a lemon plantation. The heights of the transmitter and receiver are hereby considered to be below tree height. The model was used to compare measurements performed in the citrus plantation in the 1800 and 2100 MHz frequency bands. A layered approach in the Vertical Plane (VP) and the Horizontal Plane (HP) was assumed. In the VP, we used a homogeneous medium with relative permittivity instead of soil. In the HP, we represented the trees as an equivalent continuous medium with effective permittivity. We find that a simple model including direct and reflection-from-soil contributions is enough to estimate the path loss within 10 m. To estimate accurate path loss beyond this distance, however, it becomes necessary to incorporate direct, reflected-from-soil, and reflected-from-trees contributions.