Noise reduction and signal path loss analysis of FM transmission in hilly terrain of Nepal: Case study of Dolakha

This paper investigates the effects of terrain-induced signal loss on FM radio transmission for community radio stations operating in the hilly regions of Nepal, with a specific focus on Dolakha district. Using terrain profiling through Google Earth and signal modeling with Free Space Path Loss (FSPL) along with knife-edge diffraction loss assumptions, we simulate the received signal strength at various distances from a 100 MHz FM transmitter in Charikot. The results demonstrate critical signal degradation in NLoS areas due to terrain obstructions. Based on the findings, repeater stations and directional antennas are recommended to optimize signal delivery in shadowed zones. Received: July 7, 2025 Accepted: July 23, 2025 DOI: https://dx.doi.org/10.17654/0973700626001