Sirio Antenna Test — Long-Range Performance with a Low-Horizon Satellite 

This project was both a challenge and a valuable learning experience. Together with friends from AMSAT, I set out to experiment with receiving satellite signals at very low elevation angles — an especially demanding scenario for ground communications.

For the test, we used a Sirio antenna tuned at 155-6 MHz, close to the 169 MHz target frequency of interest. To track satellites, we relied on TinyGS for decoding and GPredict for real-time orbital tracking.

Although we attempted to capture signals, the geometry of the pass made the experiment particularly difficult: satellites near the horizon in LEO orbit are typically more than 2,000 km away. Under these conditions, our setup wasn’t able to establish reliable reception.

To investigate further, we relocated the setup to a laboratory in France — one of the most reliable testing facilities in Europe in my opinion.

There, the antenna was analyzed using an older but highly precise measurement instrument. We assessed power levels, spectrum response, and frequency stability with great care. This process revealed a key issue: poor-quality soldering connections, which likely degraded the antenna’s performance and impacted our initial trials.

Despite the challenges, the project has been a valuable step toward understanding the limitations and requirements of long-range ground reception. Every unsuccessful attempt is also an opportunity to refine the approach, and this test has highlighted both the importance of careful assembly and the potential of targeted antenna design for satellite IoT applications.

“The test was unsuccessful… but that’s okay — we wrapped it up with friends and went out for drinks :)”