Height of antenna A (AGL)		meters feet
Ground elevation at antenna site A (AMSL)		meters feet
Height of antenna B (AGL)		meters feet
Ground elevation at antenna site B (AMSL)		meters feet
Enter the total path distance		kilometers meters miles feet
Enter the K factor

AGL  Above Ground Level.  Height above common ground to the the mid-point of the radiating antenna.

AMSL  Above Mean Sea Level.  Height referenced above sea level, or zero elevation.

The K factor accounts for refraction of radio waves close to the surface of the earth.  For antenna towers less than a couple of thousand feet above the surface, a K factor of 1.33 is usually adequate for most line-of-sight calculations over average terrain.

Typical Values of K

                                        Summer  Winter

Dry mountains (above 1500 meters)       1.20    1.20
Mountains (to 1500 meters)              1.25    1.25
Midwest and Northeast                   1.50    1.30
South and West Coast                    1.55    1.35
Southern Coast                          1.60    1.50