Therefore the beacon is reached directly from the downwind position unless it is initially approached directly from the upwind position.
If I am understanding this comment correctly it means that:
Experiment 1. If the starting point is with the aircraft 10 km directly upwind of the beacon it’s final approach to the beacon will be from directly upwind.
Experiment 2. If we repeat the experiment, but with the aircraft displaced even a small distance (1 m, 1 cm or even 1 mm) to the left or right, it’s final approach to the beacon will be from directly downwind.
Is this really the case?
The limits of the resolution of the ADF system should not be a factor in this, because the same equations have been applied to other situations such as the dog and hare.