Experimental Evaluation of Antenna Height Impact on LoRaWAN Performance in the 915 MHz ISM Band

The objective of this work is to examine the effect of transmitter antenna height on the performance of LoRaWAN operating in the 915 MHz ISM band under realistic outdoor conditions. Reliable long-range communication is a critical requirement for Internet of Things (IoT) applications, and antenna placement represents an important factor influencing coverage and stability. To evaluate this, field experiments were conducted at Universiti Teknikal Malaysia Melaka (UTeM) using custom-designed LoRa nodes equipped with Global Positioning System (GPS) modules to enable precise geolocation data logging. The receiver was placed inside a moving vehicle to replicate dynamic IoT data collection scenarios. Measurements of the Received Signal Strength Indicator (RSSI) were obtained for three different antenna heights: 1.5 m, 5 m, and 10 m. Experimental results reveal that elevating the antenna significantly improves RSSI values, thereby enhancing signal coverage, reducing attenuation, and extending communication range. In particular, the 10 m antenna placement yielded the most stable and reliable connections across larger distances, demonstrating its suitability for large-area IoT deployments. The findings provide empirical evidence on the influence of antenna height in LoRa systems and highlight practical considerations for network planning.