Diagram illustrating the geometry we assume in the free-free absorption modelling. The magnetic field dipole is shown in grey. We place the emitter above the magnetic pole and assume the emission propagates radially outwards along the line of sight, to ensure the most conservative mass-loss upper limit of all possible geometries. The emission region (shown in blue) is assumed to be as close to the observer as possible, to minimise the free-free absorption along its path (black arrow) to the detector (shown here as a representation of LOFAR).