Satellite Coverage Calculator
Calculate ground coverage radius, footprint surface area, central angle, and maximum slant range for a given satellite altitude and minimum elevation angle.
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Math
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Enter parameters and click Calculate to view results
Formula & Theory
ψ = arccos[(Rₑ / (Rₑ + h)) × cos(e)] - e, d_ground = Rₑ × ψ, Area = 2πRₑ²(1 - cos ψ)This formula is used to calculate antenna parameters for satellite coverage calculator.
Overview
This satellite coverage calculator determines the ground footprint radius, central Earth angle, coverage surface area, and maximum slant range for any satellite altitude and minimum elevation angle. It is built for RF engineers, HAM satellite operators, and students sizing link budgets, ground station visibility windows, and antenna pointing requirements for LEO, MEO, and GEO systems.
Input Guide
Enter Satellite Altitude, Minimum Elevation Angle exactly in the units shown by this satellite coverage. 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 Angle — use °.
Output Guide
The results describe the calculated satellite coverage 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 Coverage uses ψ = arccos[(Rₑ / (Rₑ + h)) × cos(e)] - e, d_ground = Rₑ × ψ, Area = 2πRₑ²(1 - cos ψ). Supply Satellite Altitude (km), Minimum Elevation 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 minimum elevation angle functions as a horizon mask for your ground station antenna. Below roughly 5°–10°, the signal path traverses far more atmosphere, terrain, and man-made clutter, so most fixed and tracking ground stations set a practical mask between 5° and 15° depending on antenna gain, local terrain, and link margin. Raising the elevation mask shrinks the usable footprint but improves signal quality by reducing tropospheric scintillation, rain fade, and multipath from nearby structures — a tradeoff every satellite station designer has to balance against pass duration and coverage area.
Build and Tuning Notes
The maximum slant range reported here occurs at the minimum elevation boundary, which is also the worst-case point for free-space path loss (FSPL) and Doppler shift in a LEO pass. Use this edge-of-coverage distance when sizing your link budget, antenna gain, and receiver sensitivity — if your system closes the link at maximum slant range, it will close comfortably at higher elevations closer to zenith. For HAM satellite work (e.g., FM, SSB, or digital LEO passes), this figure also helps predict how long a satellite will remain above your horizon mask and how much your Doppler correction needs to shift over the pass.
Frequently Asked Questions
Why does my ground station need a minimum elevation angle?
Signals arriving below about 5°–10° elevation pass through significantly more atmosphere, which increases noise temperature, rain fade, atmospheric absorption, and multipath from terrain or buildings near the horizon. Setting a minimum elevation mask keeps your link budget realistic and avoids chasing satellites through unusable, noisy geometry.
How much of Earth can one satellite actually see?
It depends heavily on altitude. A LEO satellite around 550 km typically covers only about 1.5%–3% of Earth’s surface at any instant, which is why LEO constellations need many satellites for continuous coverage. A GEO satellite at roughly 35,786 km, by contrast, can cover close to 42% of the surface from a single fixed orbital slot — though usable elevation angles near the edge of that footprint are often too low for reliable links.
What exactly is the central angle (ψ), and why does it matter?
The central angle is the angle measured at Earth's center between the sub-satellite point (directly below the satellite) and the outer edge of the visible coverage footprint. It directly sets both the ground coverage radius and the pass geometry your antenna will need to track, making it the key variable behind footprint size, slant range, and pass duration.
How does slant range affect antenna and power budget design?
Slant range is the true line-of-sight distance to the satellite, which is always longer than the straight-line altitude except at zenith. Free-space path loss scales with the square of this distance, so the maximum slant range at your elevation mask sets the worst-case attenuation your antenna gain, transmit power, and receiver sensitivity must overcome for a reliable link across the entire pass.
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.