Transient analysis of a space-borne microstrip patch antenna illuminated by an electromagnetic pulse

The transient response of a microstrip patch antenna excited by a plane wave is studied using a finite difference algorithm applied to a total field version of Maxwell´s curl equations in the time domain. A wide bandwidth study shows different behavior in the antenna, depending on the frequency and angle of incidence of the wave. At low frequencies, the voltage in a 50 Ω load is proportional to the derivative of the incident Eⁱ field. With increasing frequency, parasitic oscillations appear to be due to the short-circuited patch. In addition, at high frequencies, antenna sizes and wavelength are of the same order. The voltage contains oscillations at the frequency of the TM mode of the antenna. Two patterns of coupling appear: (1) capacitive coupling, where the current on the patch rises at the wire-metallic plane junction and spreads on the patch and on the finite ground plane; and (2) coupling due to the scattering, where the current rises at the edges of the patch and on the finite ground plane