Satellite Path Loss Calculator
Calculate free-space path loss (FSPL), wavelength, and atmospheric loss context for satellite radio links.
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Math
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Enter parameters and click Calculate to view results
Formula & Theory
FSPL (dB) = 92.4478 + 20 log₁₀(f_GHz) + 20 log₁₀(d_km), λ = c / fThis formula is used to calculate antenna parameters for satellite path loss calculator.
Overview
Use this satellite path loss calculator to compute free-space path loss (FSPL) and signal wavelength for RF communication links spanning L, C, X, Ku, Ka, and Q/V bands.
Input Guide
Enter Frequency, Slant Range exactly in the units shown by this satellite path loss. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Frequency — use GHz.
- Slant Range — use km.
Output Guide
The results describe the calculated satellite path loss 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 Path Loss uses FSPL (dB) = 92.4478 + 20 log₁₀(f_GHz) + 20 log₁₀(d_km), λ = c / f. Supply Frequency (GHz), Slant Range (km) in the displayed units, then use the calculated values as the first engineering target for this satellite communication design or analysis.
Design Notes
Free-space path loss represents the geometric spreading of electromagnetic energy as it radiates through vacuum. For geostationary satellites (~38,000 km slant range), FSPL typically ranges from ~170 dB at L-band up to ~215+ dB at Ka-band.
Build and Tuning Notes
FSPL accounts only for vacuum spreading. Real-world satellite link budgets must add atmospheric gas absorption (O₂ and water vapor) and rain attenuation, especially for frequencies above 10 GHz.
Frequently Asked Questions
Why is free-space path loss so high for satellites?
Path loss scales with the square of both distance and frequency (20 log₁₀(d) + 20 log₁₀(f)). Because satellites operate over thousands of kilometers, geometric signal spreading creates very high attenuation.
What constant is used in the FSPL formula for GHz and km?
The constant 92.4478 dB is derived from 20×log₁₀(4π × 10¹² / c), where c ≈ 299,792,458 m/s is the speed of light in vacuum.
Does rain fade affect all satellite bands equally?
No. Frequencies below 3 GHz (L/S bands) experience negligible rain fade. Frequencies above 10 GHz (Ku/Ka bands) suffer severe rain attenuation because raindrop sizes approach the wavelength of the signal.
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.