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HAAT, elevation and max ERP calculator
Give it an antenna location and height. It returns the ground elevation, the antenna's height above average terrain along each of the FCC's eight radials, plus the maximum power allowed there for an LPFM, an FM translator or each FM class.
You can also enter the details by hand below.
Enter a U.S. latitude and longitude (NAD83), in decimal degrees or degrees, minutes and seconds.
Want the complete study?
Every application begins with HAAT. RF Navigator, which is the engineering software powering this calculator, handles the rest: contour protection, channel searches, interference and the FCC exhibits. Or have Nexus Broadcast take on the engineering.
How the calculator works
- Ground elevation and terrain are taken from the FCC's terrain data (geo.fcc.gov), based on USGS 1 arc-second elevation data. For each radial, HAAT equals the radiation center less the mean terrain between 3 and 16 km (§73.313(d)).
- HAAT averages eight radials spaced 45° apart starting at true north (§73.313(d)(1)). When an ERP is given, radials crossing foreign territory or a large body of water are kept, shortened or removed according to §73.313(d)(2).
- Class limits follow §73.211: each class's maximum ERP and reference HAAT, plus the lower ERP needed above that reference HAAT so the reference distance (the 1 mV/m point per §73.333 on the FCC F(50,50) curves, to the nearest whole km) stays within the class contour.
- For LPFM the limits are from §73.811; for FM translators they come from the §74.1235(b) tables for whichever side of the Mississippi River the site is on.
- Coastlines and zone boundaries are plotted from public map data. Sites near a zone boundary are flagged so you can verify the zone.
Intended for planning. Not an FCC product; confirm with the FCC's tools and an engineer prior to filing.