Transient Behavior of Aperture Antennas

The transient behavior of aperture antennas is analyzed. For an antenna which is illuminated by a field of uniform phase and either uniform or cosine tapered amplitude, it is shown that the steady-state main lobe is established within (¿/2+R/c) seconds after the aperture is energized. ¿ is the period of the carrier frequency, R is the distance from the center of the aperture to the point where the field is evaluated, and c is the velocity of light. The time required for the establishment of the steady-state pattern at all angles between 0° and 90° is (¿/2¿0+ R/c) where 2¿0 radians is the beamwidth between first nulls of the steady-state pattern (¿0<\n\n\t\t