FREQUENCY COORDINATING COMMITTEE

HAAT HOW-TO

The following article will help you use the FCC's free online HAAT calculator, using the data that is expected to be input.

While the FCC's calculator is accurate, it's not very user friendly, but it's free.

Height data must be input in Meters - not Feet. As such, you must convert Feet to Meters. Thankfully, Google Search makes this part of the process very easy.

Google Earth is one method of coming up with your exact Longitude and Latitude coordinates. By default, Google Earth displays LAT and LONG as decimal degrees. You must change the display to Degrees, Minutes, Seconds. The do this, go under the Tools tab and select Options..., then click on the bullet Degrees, Minutes, Seconds under the "Show Lat/Long" section. Google Earth will then show you the Degrees, Minutes, Seconds and Ground Elevation data at the bottom of the image. There is no easy way to copy and paste this data, so make sure you write it down correctly after navigating to your sites exact location.

The following examples will show you how to precisely calculate HAAT for the given LAT/LONG.

Lets say your site is located at precisely 40° 0' 0" by 80 ° 0' 0". This location is near the intersection of Mulberry Street and Potters Alley in the town of Fredericktown PA (about 27 miles south of Pittsburgh). Navigating to the precise location reveals the Ground Elevation of 910 Feet. Lets say your antenna is 100 feet above the ground, add 910 and 100 to get the sum of 1010 Feet. This SUM is input as "RCAMSL" in the FCC website - RCAMSL is your antenna height above mean sea level in Meters.

Go to Google and enter "1010 feet in meters" and hit the enter key. The answer will be revealed, 307.8 Meters.

You now have all of the information necessary to properly calculate HAAT for this location with an antenna height of 100 feet above the ground.

Go to the FCC's online HAAT Calculator website.
Enter the LAT/LONG coordinates

Click "NAD83/WGS84 (worldwide)" button

Enter 307.8 in the "Enter the height (in meters) of the antenna radiation center above mean sea level (RCAMSL)" box.

Click the "8" radial button

Click "FCC Terrain Data" - button

Click the "Send Data" button

The following result will be revealed.

Calculated HAAT= -18. meters

Notice the result says -18 meters. That's MINUS 18 meters or in other words 18 meters BELOW average terrain.

To convert -18 meters to feet go back to Google and enter "-18 meters in feet" and hit the enter key. This converts to -59 feet HAAT.

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Lets say your site is located at precisely 40° 0' 0" by 79 ° 0' 0". This location is about 2 miles east of the Route 219 and Route 70 (Turnpike) intersection in Somerset County. Navigating to the precise location reveals the Ground Elevation of 2410 Feet. Lets say your antenna is 100 feet above the ground, add 2410 and 100 to get the sum of 2510 Feet. This SUM is input as "RCAMSL" in the FCC website - RCAMSL is your antenna height above mean sea level in Meters.

Go to Google and enter "2510 feet in meters" and hit the enter key. The answer will be revealed, 765 Meters.

You now have all of the information necessary to properly calculate HAAT for this location with an antenna height of 100 feet above the ground.

Go to the FCC's online HAAT Calculator website.
Enter the LAT/LONG coordinates

Click "NAD83/WGS84 (worldwide)" button

Enter 765 in the "RCAMSL" box.

Click the "8" radial button

Click "FCC Terrain Data" - button

Click the "Send Data" button

The following result will be revealed.

Calculated HAAT= 79. meters

Notice the result is positive this time.

To convert 79 meters to feet go back to Google and enter "79 meters in feet" and hit the enter key. This converts to 259 feet HAAT.

Now, substitute your LAT / LONG, ground elevation, and antenna height (to input RCAMSL in meters) and compute your HAAT. Use that result in the HAAT field on the WPRC Form 100.

**Page created: January 1, 2014 - W3KKC**

Updated April 2015 to match the changed FCC website submission process.