Community Radio for Lessons: Coverage Radius and Cost per Learner Reached

A low-power FM transmitter can carry lessons to learners with no books and no network. This paper computes the radio-horizon coverage of a 30 metre mast, converts the covered area into learners reached under stated density and access assumptions, and prices the transmitter per learner. Terrain shadowing will cut the idealised area, and the paper states the discount a planner should apply rather than hiding it. Computed results: horizon_km = 24.6, coverage_km2 = 1902, learners_reached = 22819, cost_per_learner_usd = 0.11, tx_power_W = 50. Every number in this paper is produced by the accompanying script `compute.py`. SIMULATED, NOT MEASURED.