Doppler radar installed during the 1990s by the Federal Aviation Administration at U. S. Airports with high traffic density or susceptibility to wind shear. Radars are located 10–20 km from the airports in order to detect microbursts, gust fronts, and convective storms along arrival and departure paths. The nominal transmitted wavelength of the TDWR is 5. 3 cm (C band) and the nominal circular beamwidth is 0. 5°.