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HAAT, elevation and max ERP calculator
Enter an antenna site and height. You get the ground elevation, antenna height above average terrain on the FCC's eight radials, and the most power each FM class, an LPFM or an FM translator can run there.
Need the full study?
HAAT is where an application starts. RF Navigator, the engineering software behind this calculator, runs the whole job: channel searches, contour protection, interference and the exhibits the FCC wants. Or let Nexus Broadcast do the engineering for you.
How this calculator works
- Terrain and ground elevation come from the FCC's terrain service (geo.fcc.gov), using USGS 1 arc-second elevation data. Each radial's HAAT is the radiation center minus the average terrain from 3 to 16 km (§73.313(d)).
- HAAT is the average of eight radials every 45° from true north (§73.313(d)(1)). With an ERP entered, radials over a large body of water or foreign territory are included, shortened or dropped as §73.313(d)(2) requires.
- Class limits are from §73.211: the maximum ERP and reference HAAT for each class, and the reduced ERP above the reference HAAT that keeps the reference distance (1 mV/m on the FCC F(50,50) curves, §73.333, rounded to the nearest km) inside the class contour.
- LPFM limits follow §73.811; FM translator limits follow the §74.1235(b) tables for the site's side of the Mississippi River.
- Zone lines and coastlines are drawn from public map data. A site close to a zone line gets a note to confirm the zone.
For planning. Not a product of the FCC; check the FCC's own tools and an engineer before you file.