What type of radar antenna has multiple individual slot radiators distributed over a flat surface?

The correct answer is the planar array. A planar array antenna features an arrangement of multiple individual slot radiators that are distributed across a flat surface. This design allows for effective beamforming and electronic scanning, which enhances the radar's ability to detect and track targets over a wide area.

In contrast, parabolic antennas typically utilize a single reflective surface to focus incoming signals onto a receiver, and they are not characterized by the multiple slot configuration. Dish antennas, while similar to parabolic antennas in their reflective surface application, do not consist of multiple individual radiators on a flat surface. Log-periodic antennas also differ, as they use a series of elements of different lengths to achieve wide bandwidth, but they do not have the flat, multi-slot arrangement associated with planar arrays. Thus, the unique structure of the planar array makes it particularly suitable for advanced radar applications that require high-frequency operation and nimble beam direction.