The effect detailed in this comment and its parent is the Fresnel Zone [1], which isn't quite direct, human intuition 'line-of-sight', but that concept applied

The effect detailed in this comment and its parent is the Fresnel Zone [1], which isn't quite direct, human intuition 'line-of-sight', but that concept applied to RF waves. Essentially, any object intruding into a blimp-shaped region between the receiver and the transmitter has the potential to mess things up, and is corrected by having a payload in the signal that's tolerant or self-correcting of errors. [1] https://en.wikipedia.org/wiki/Fresnel_zone https://en.wikipedia.org/wiki/Fresnel_zone