The near-Earth asteroids (NEAs) are a population of objects on orbits around the Sun that pass near or cross that of Earth. They are probes of solar system history, accessible targets for spacecraft missions, and a potential hazard to life on Earth. Ground-based radar observations with large radio telescopes provide the extremely accurate astrometry and trajectory predictions for near-Earth asteroids. They also provide detailed information on the shapes, spin states, and surface properties of a large number of objects; giving essential context for spacecraft missions to asteroids. I will describe the techniques of planetary radar astronomy and review the capabilities of radar observations from the Arecibo Observatory, the Goldstone Deep Space Network site, the Green Bank Telescope, and the Very Long Baseline Array. Then I will detail the physical properties of a few asteroid radar targets; including Toutatis, visited by the Chang'e 2 spacecraft in 2012, and Bennu, target of NASA's upcoming OSIRIS-REx mission.