Assertion: radar's antenna | /r/CapableOf | look for object
Facets:
Source sentences:
text: Three systems are generally used; the most common uses the ionosphere as a reflector and beams the signal skyward and then listens for the tiny signals that are returned from the sky, others use a bistatic arrangement with distant antennas looking for objects that pass between them, and a small number of systems use "creeping waves" that travel into the shadow zone.