A satellite ground station link budget uses the same building blocks as any radio link, with a few specific figures of merit.

Receive side: G/T
The receive figure of merit is G/T (dB/K): antenna gain divided by system noise temperature, referred to the same point (commonly the LNA input). System noise temperature includes antenna noise temperature (sky, ground spill-over, rain), feed losses and LNA noise temperature. Losses before the LNA add noise directly, which is why the LNA or LNB is mounted at the feed.

Carrier-to-noise density:
C/N0 = EIRP - path loss - other losses + G/T - k (dB), where k is Boltzmann's constant, -228.6 dBW/K/Hz.
Then C/N = C/N0 - 10*log10(bandwidth). Required Eb/N0 depends on modulation and coding.

Typical chain
- Receive: feed horn and orthomode transducer -> LNA or LNB (low-noise block downconverter to L-band IF) -> coax or fiber -> modem.
- Transmit: modem L-band IF -> BUC (block upconverter with PA) -> feed -> antenna.

Why L-band IF over fiber?
Long coax runs at L-band lose significant signal and need amplification. RF-over-Fiber links carrying L-band between the antenna and the equipment room are a common solution at larger sites, giving low loss over long distances and electrical isolation (useful for lightning protection).

Other factors
- Rain fade, especially at Ku and Ka band; ITU-R P.618 provides methods for predicting rain attenuation on Earth-space paths.
- Pointing loss and antenna tracking for LEO constellations.
- Phase noise of the LO in LNBs and BUCs, which matters for higher-order modulation.
- Interference and cross-polarization isolation.

Start with a spreadsheet budget, then verify with measured G/T (for example, using the Y-factor method with cold sky and ambient loads).