Satellite Downlink Calculator
Calculate ground station received power (dBW/dBm), system figure of merit (G/T), and carrier-to-noise density ratio (C/N₀) for a satellite downlink.
5
Inputs
Live
Math
3
Related
Enter parameters and click Calculate to view results
Formula & Theory
P_r = EIRP - FSPL - L_misc + G_r, C/N₀ = P_r - k - T_sys (dBHz)This formula is used to calculate antenna parameters for satellite downlink calculator.
Overview
Use this satellite downlink calculator to evaluate received carrier power and link budget parameters for Earth station receivers across C, Ku, Ka, and L bands.
Input Guide
Enter Satellite Downlink EIRP, Downlink Path Loss (FSPL), Ground Station Antenna Gain, Atmospheric & Pol Losses, System Noise Temp (T_sys) exactly in the units shown by this satellite downlink. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Satellite Downlink EIRP — use dBW.
- Downlink Path Loss (FSPL) — use dB.
- Ground Station Antenna Gain — use dBi.
- Atmospheric & Pol Losses — use dB.
- System Noise Temp (T_sys) — use K.
Output Guide
The results describe the calculated satellite downlink 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 Downlink uses P_r = EIRP - FSPL - L_misc + G_r, C/N₀ = P_r - k - T_sys (dBHz). Supply Satellite Downlink EIRP (dBW), Downlink Path Loss (FSPL) (dB), Ground Station Antenna Gain (dBi), Atmospheric & Pol Losses (dB), System Noise Temp (T_sys) (K) 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 power budget sums satellite Effective Isotropically Radiated Power (EIRP), free-space path loss (FSPL), atmospheric/polarization losses, and ground station antenna receive gain (G_r).
Build and Tuning Notes
To verify demodulator lock capability, combine received power with ground station system noise temperature (T_sys) to compute Carrier-to-Noise Density (C/N₀) and Figure of Merit (G/T).
Frequently Asked Questions
What is the relationship between dBW and dBm in satellite downlinks?
0 dBW equals +30 dBm. A typical GEO downlink signal arrives at the ground station dish at around -115 dBW to -135 dBW (-85 dBm to -105 dBm).
What is G/T (Figure of Merit)?
G/T (dB/K) measures ground station receiving performance. It is the antenna receive gain in dBi minus 10×log10 of the total system noise temperature in Kelvin.
What is Boltzmann’s constant in dB format?
Boltzmann’s constant k = 1.380649 × 10⁻²³ J/K, which converts to -228.6 dBW/(Hz·K) in logarithmic link budget equations.
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.