Satellite Link Budget Calculator
Calculate total link loss, incident power, C/N₀, Carrier-to-Noise Ratio (C/N), and Eb/N₀ for satellite communication links.
5
Inputs
Live
Math
3
Related
Enter parameters and click Calculate to view results
Formula & Theory
C/N₀ = EIRP - FSPL - L_misc + G/T + 228.6 (dB-Hz), C/N = C/N₀ - 10 log₁₀(B_Hz)This formula is used to calculate antenna parameters for satellite link budget calculator.
Overview
Use this satellite link budget calculator to evaluate RF power levels, path attenuation, carrier-to-noise density (C/N₀), and signal-to-noise ratios (C/N and Eb/N₀) across L, C, Ku, and Ka satellite bands.
Input Guide
Enter Transmit EIRP, Path Loss (FSPL), Receive G/T, Atmospheric & Misc Losses, Channel Bandwidth exactly in the units shown by this satellite link budget. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Transmit EIRP — use dBW.
- Path Loss (FSPL) — use dB.
- Receive G/T — use dB/K.
- Atmospheric & Misc Losses — use dB.
- Channel Bandwidth — use MHz.
Output Guide
The results describe the calculated satellite link budget 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 Link Budget uses C/N₀ = EIRP - FSPL - L_misc + G/T + 228.6 (dB-Hz), C/N = C/N₀ - 10 log₁₀(B_Hz). Supply Transmit EIRP (dBW), Path Loss (FSPL) (dB), Receive G/T (dB/K), Atmospheric & Misc Losses (dB), Channel Bandwidth (MHz) in the displayed units, then use the calculated values as the first engineering target for this satellite communication design or analysis.
Design Notes
The link budget determines whether a wireless communications link between a satellite and Earth station will operate reliably. The constant 228.6 dBW/(Hz·K) represents -10×log₁₀(k), where k is Boltzmann’s constant (1.380649 × 10⁻²³ J/K).
Build and Tuning Notes
To verify if a digital link will close, compare the calculated C/N or Eb/N₀ against your modem’s required threshold (QPSK, 8PSK, 16APSK, etc.) plus an operational fade margin (typically 3–6 dB).
Frequently Asked Questions
What is the difference between C/N₀ and C/N?
C/N₀ (Carrier-to-Noise Density ratio) measures carrier power relative to noise in a 1 Hz bandwidth (expressed in dB-Hz). C/N (Carrier-to-Noise ratio) measures carrier power relative to total noise power across the full modulated channel bandwidth (expressed in dB).
How do you convert C/N₀ to Eb/N₀?
Subtract 10×log₁₀(Data Rate in bit/s) from C/N₀. Eb/N₀ (Energy per bit to spectral noise density) allows direct comparison of modulation efficiency independently of bandwidth.
Where does the +228.6 constant come from in link budget equations?
It is the logarithmic representation of Boltzmann’s constant: -10×log₁₀(1.380649 × 10⁻²³ J/K) ≈ +228.6 dBW/(Hz·K).
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.