Millimeter-wave radar generates a narrower beam than conventional microwave radar, making it less vulnerable to antiradar missiles than conventional radar.

(a) Calculate the angular width 20 of the central maximum, from first minimum to first minimum, produced by a 220 GHz radar beam emitted by a 55.0-cm-diameter circular antenna. (The frequency is chosen to coincide with a low-absorption atmospheric "window.")

(b) What are 20 for a more conventional circular antenna that has a diameter of 2.3 m and emits at wavelength 1.6 cm?