This paper investigates the impact of antenna design on the performance of LoRa communication systems through experimental and simulation-based analysis of three antenna models: a commercial omnidirectional antenna, a manually constructed Yagi antenna, and a simulation-optimized Yagi antenna, all designed for 868 MHz operation. The study focuses on evaluating critical communication parameters, including received signal strength (RSSI), signal-to-noise ratio (SNR), voltage standing wave ratio (VSWR), and packet loss under real-world conditions over a 2 km line-of-sight rural test range. The results demonstrate that directional Yagi antennas, especially those optimized via electromagnetic simulation tools, significantly outperform omnidirectional models in terms of signal reliability and link efficiency. The findings confirm that the integration of open-source design tools and accessible fabrication technologies enables the development of high-performance antennas suitable for deployment in decentralized, long-range IoT infrastructures.