Satellite Footprint Calculator
Calculate the coverage footprint radius, central earth angle, surface area, and maximum slant range for any satellite altitude and elevation mask.
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Inputs
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Math
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Related
Enter parameters and click Calculate to view results
Formula & Theory
ψ = arccos[(Rₑ / (Rₑ + h)) × cos(θ)] - θ, Footprint Radius = Rₑ × ψ, Area = 2πRₑ²(1 - cos ψ)This formula is used to calculate antenna parameters for satellite footprint calculator.
Overview
Use this satellite footprint calculator to compute the maximum Earth surface coverage radius, central angle, and geographical surface area visible from a satellite in LEO, MEO, or GEO orbit.
Input Guide
Enter Satellite Altitude, Minimum Elevation Mask Angle exactly in the units shown by this satellite footprint. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Satellite Altitude — use km.
- Minimum Elevation Mask Angle — use °.
Output Guide
The results describe the calculated satellite footprint values for the inputs you entered. Check each value against the available space, selected components, feed system, and operating conditions before making a final design decision.
How This Calculator Works
The Satellite Footprint uses ψ = arccos[(Rₑ / (Rₑ + h)) × cos(θ)] - θ, Footprint Radius = Rₑ × ψ, Area = 2πRₑ²(1 - cos ψ). Supply Satellite Altitude (km), Minimum Elevation Mask Angle (°) in the displayed units, then use the calculated values as the first engineering target for this satellite communication design or analysis.
Design Notes
The theoretical footprint assumes a line-of-sight tangent to the Earth (0° elevation angle). In real-world satellite link design, an elevation mask angle (e.g., 5°–10°) is applied to ensure signals clear buildings, terrain, and heavy atmospheric noise near the horizon.
Build and Tuning Notes
At geostationary orbit (35,786 km), a single satellite’s theoretical footprint covers up to ~42.4% of the Earth’s surface (~216 million km²), requiring three evenly spaced satellites to achieve global equatorial coverage.
Frequently Asked Questions
What is the maximum Earth surface area a GEO satellite can cover?
A single geostationary satellite at 35,786 km altitude can view a maximum theoretical central angle of ~81.3°, covering roughly 42.4% of the total Earth surface area.
Why does an elevation mask shrink the satellite footprint?
Ground receivers require a minimum angle above the horizon (typically 5° to 15°) to maintain link quality. Increasing the elevation mask reduces the usable central angle, shrinking the effective footprint radius.
What is the sub-satellite point?
The sub-satellite point is the precise geographic location on Earth’s surface directly beneath the satellite (nadir point), where the elevation angle is exactly 90°.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.