Earth-Moon Link Budget Calculator

Estimate whether a simplified radio link closes across lunar distance. Unlike the communication-delay tool, this calculator addresses signal strength and data rate rather than propagation time.

Method

The calculator uses ideal parabolic-dish gain, free-space path loss and a thermal-noise model. It calculates carrier-to-noise-density ratio and converts that to energy per bit to noise density, or Eb/N0, at the selected data rate.

Free-space path loss: 20 log10(4πd/λ). Dish gain: 10 log10[η(πD/λ)²]. Link margin is the estimated Eb/N0 minus the required Eb/N0 you enter.

What the estimate leaves out

A flight link budget can include atmospheric loss, pointing loss, polarization mismatch, implementation loss, coding gain, modulation details, weather, antenna pattern, ground-station elevation and hardware margins. This calculator is a teaching model for the dominant relationships, not a communications certification tool.