Attached is an EXCEL spreadsheet where you fill in the following information:
1) Site #1, Lat/Long in Deg/Min/Sec (Get from google map or google earth)
2) Site #2, Lat/Long in Deg/Min/Sec (Get from google map or google earth)
3) Transmit Frequency
4) Site #1 & #2, Antenna Gain
5) Site #1 & #2, Antenna Gain
6) Site #1 & #2, Miscellaneous Losses (ie, cable loss)
7) Transmit Power
8) Main Obstacle Height (ie, Hill, Building, etc) in ft
9) Approximate Distance to Obstacle in miles
Look for a Typical Received Signal Level above 3 microvolt for successful contact. This will also calculate the path distance in both Miles and Kilometers. This will help give you a good idea of what is needed for reliable ground wave coverage.
Have fun!
Mike