SFD
Pronunciation: ESS-EFF-DEE
Also written as: SFD — Saturation Flux Density
The power flux density (in dBW/m²) arriving at a satellite's receive antenna that drives the satellite's transponder to full (saturated) output power.
Full Definition
Saturation Flux Density is a satellite transponder parameter that defines the uplink signal strength required to bring the transponder amplifier to saturation—its maximum rated output power. SFD is expressed in dBW/m² and is a critical input for ground station uplink power control settings. Editors will encounter SFD in ITU filings, IOT reports, and transponder specification sheets. Confusing SFD with EIRP is a common editorial error: SFD is an uplink receive parameter, while EIRP is a transmit parameter. SFD values are typically negative numbers (e.g., −87 dBW/m²).
Usage
Usage note: Always express in dBW/m². Do not confuse with PFD (Power Flux Density), which is a different regulatory parameter. Negative values are normal and should not be 'corrected' by an editor.
In Context
- "The transponder's SFD of −88 dBW/m² required the ground station to uplink at precisely controlled power levels." — Transponder specification sheet
- "Editors reviewing link budgets should verify that the SFD figure matches the value declared in the satellite's ITU filing." — Document quality review