The angle between the half-power points of the main beam of the radiation pattern of an an...

The angle between the half-power points of the main beam of the radiation pattern of an antenna is often called the beamwidth of the pattern. (Half-power points are points at which the field strength is  of that in the direction of maximum radiation.) Find the beamwidth of the E-plane pattern of (a) a Hertzian dipole, and (b) a half-wave dipole.