A circular patch with a single feed point will create linearly-polarized radiation.

A circular patch of hair on the central pad of their hind paws marks plantar glands that give off a distinctive odor.

It causes strange circular patches on the skin, especially on the knuckles, back of the feet and sometimes on the arms and legs too.

During the winter and into the spring seasons, well-defined, clustered, circular patches 10-20 cm in diameter, of necrotic leaf tissues form on mown turf.

Palimpsests are bright, nearly circular patches that are believed to be remnant impact features.