Measurement of Attenuated LoRa Propagation in Sandy Loam

Advances in subsurface wireless sensor systems are required to understand complex chemical and biological mechanisms that govern soil formation and processes. In this work, we have experimentally investigated the attenuation effect of saturated sandy loam texture soil on LoRaWAN signal strength in the frequency of operation of 915 MHz. We have reported experimental results of RSSI (Received Signal Strength Indicator) and SNR between two LoRaWAN sensors, one buried in sandy loam from depths of 0 to 40 (cm) with moisture contents ranging from 10% to 50%, to an above soil sensor with a free space path distance of 2 (m) away. The attenuation variations in terms of the dielectric properties of the soil obtained by the proposed measurement set-up have been compared to theoretical results of the path loss model of Peplinski and Dobson. There is good agreement between measurement and theoretical results at a 40 (cm) burial depth, at 30 (cm) after 30% moisture, and 20 (cm) at moisture contents of 20% and 40%.