Computing Radar Horizon |
Precomputed Radar Horizons
Ticonderoga CG AN/SPY-1 (50 ft above SL)
17~ nm vs target at 50 ft
95~ nm vs
target at 5,000 ft
200~ nm vs target at 25,000 ft
283~ nm vs
target at 50,000 ft
397~ nm vs target at 100,000 ft
713~ nm vs
target at 328,000 ft (100 km)
1,800~ nm (3,336 km) vs target at
648 km (Thor ICBM Apogee)
AWACS (20,000 ft above SL)
179~ nm vs target
at 50 ft
260~ nm vs target at 5,000 ft
368~ nm vs target at
25,000 ft
449~ nm vs target at 50,000 ft
563~ nm vs target at
100,000 ft
878~ nm vs target at 328,000 ft (100 km)
2,401~ nm
vs target at 1,000 km (Apogee level for ICBMs)
Simplified Radar Horizon for Earth (English Units)
Radar_{Horizon} = 1.23 * sqrt (Height_{Antenna})
Radar_{Horizon} = Distance to the Radar Horizon in Nautical Miles.
Height_{Antenna} := Height of Radar Antenna in Feet.
NOTE: This equation is inaccurate compared to the full radar horizon equation, but it yields results accurate enough for “back of the envelope” work.
EXAMPLE: You have a B-70 flying at 75,000 feet; what is the maximum radar horizon of a search radar on it? 1.23 (sqrt[75,000]) 1.23 (273.86) = 336.86 nm |
Simplified Radar Horizon For Earth (Metric Units)
Radar_{Horizon} = 4.124 * sqrt (Height_{Antenna})
Radar_{Horizon}: Distance to the Radar Horizon in kilometers.
Height_{Antenna}: Height of Radar Antenna in meters.
NOTE: This equation is inaccurate compared to the full radar horizon equation, but it yields results accurate enough for “back of the envelope” work.
Complex Radar Horizon (Metric Units)
Radar_{Horizon} = sqrt (4/3) * sqrt (2 * Radius_{Planet} * Height_{Antenna})
Radar_{Horizon}: Distance to the Radar Horizon in kilometers.
Height_{Antenna}: Height of Radar Antenna in meters.
Radius_{Planet} = Radius of the planet in kilometers. (Earth is 6,378 km)
Simplified Radar Horizon Against a Target at a Specific Height for Earth (English Units)
Radar_{Horizon} = 1.23 * ( sqrt [Height_{Antenna}] + sqrt [Height_{Target}])
Radar_{Horizon} = Distance to the Radar Horizon in Nautical Miles.
Antenna_{Height} = Height of Radar Antenna in Feet.
Height_{Target} = Height of Target in feet.
NOTE: This equation is inaccurate compared to the full radar horizon equation, but it yields results accurate enough for “back of the envelope” work.
EXAMPLE: You have a EC-121 flying at 25,000 feet; what is the maximum radar horizon of a radar on the EC-121 against a target at 5,000 feet? 1.23 * (sqrt[25,000] + sqrt[5,000]) = = 281.45 nm |
Simplified Radar Horizon Against a Target at a Specific Height for Earth (Metric Units)
Radar_{Horizon} = 4.124 * ( sqrt [Height_{Antenna}] + sqrt [Height_{Target}])
Radar_{Horizon} = Distance to the Radar Horizon in kilometers
Antenna_{Height} = Height of Radar Antenna in meters.
Height_{Target} = Height of Target in meters.
NOTE: This equation is inaccurate compared to the full radar horizon equation, but it yields results accurate enough for “back of the envelope” work.