An automobile's directional lights.
A directional antenna.
Class C: Directional relation changing periodically; velocity ratio constant or varying.
Such limitation becomes soon emphatic in 2D data because of lack of an ability to capture directional singularity.
The word I focus on in the example is away, which has been traditionally called a directional adverb.
That's with the standard readers directional aerials would do better.
A few of the smaller sites just have two directional antennas at the top of a pole or on a shared tower.