Path Loss Measurements and Modelling in a Citrus Plantation in the 1800 MHz, 3.5 GHz and 28 GHz in LoS

Agriculture 4.0 is going to represent a massive deployment of sensors, so efficient planning of radiocommunication systems in this type of environment will be necessary. In this work, the measured path loss in a LoS condition, with the transmitter and receiver heights below the trees height, at a citrus plantation in the 1800 MHz, 3.5 GHz and 28 GHz frequency bands using a two-ray model in the vertical plane and the FI (Floating Intercept) and the CI (Close-In reference) slope models is analysed. Results show that, in the 28 GHz band, the direct and reflected-from-soil contribution may be enough to estimate the path loss for all the measure distance range, however, in the 1800 MHz and 3.5 GHz bands the multiple-scattering contributions from trees need to be considered after some distance between the transmitter and receiver. Furthermore, a guiding effect has been observed only in the 1800 MHz band.