Fresnel Zone API
Fresnel-zone and line-of-sight clearance maths for radio-link planning as an API, computed locally and deterministically. The radius endpoint computes the Fresnel-zone radius at any point along a path, rₙ = √(n·λ·d1·d2/(d1+d2)) with λ = c/f, together with the wavelength and the 60 % clearance that a near-free-space link needs. The midpoint endpoint gives the widest radius — the zone is fattest at the path midpoint — and its 60 % clearance, the figure you size antenna heights against. The earthbulge endpoint adds the earth-curvature bulge, h = d1·d2/(12.75·k) with k ≈ 4/3 for a standard atmosphere, and combines it with the Fresnel clearance into a total obstruction clearance for the path. Distances are in kilometres, frequency in gigahertz, radii in metres. Everything is computed locally and deterministically, so it is instant and private. Ideal for wireless, WISP, microwave-backhaul, LoRa and amateur-radio app developers, link-planning and coverage tools, and RF engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is Fresnel-zone & line-of-sight clearance; for free-space path loss and link budget use a path-loss API and for antenna gain use an antenna API.
api.oanor.com/fresnel-api
