Observations of the 21 cm HI Line from the Milky Way galaxy using Pyramidal Horn Radio Telescope

We present the design, implementation, and operation of a pyramidal horn radio telescope built for detecting the Galactic 21 cm neutral hydrogen line emission. The system employs an SDR-based pipeline to obtain drift-scan observations, which were calibrated and processed to generate HI sky maps, a Galactic rotation curve and spiral arm features. This demonstrates that this low-cost system is effective both for educational purposes and scientific exploration of Galactic structure at radio frequencies.