Analysis of the Coupling Field Inside a Rectangular Shielded Enclosure with an Aperture

The finite-difference time-domain (FDTD) method was used to study the plane wave coupling into a rectangular shielded enclosure through a aperture, and the theoretical prediction agree with the measured characteristics well. Results show that: 1) if the wave sources travel vertically to the aperture, the coupling field inside the cavity is mainly composed of different modes resonance fields; and 2) if the wave sources travel along the direction parallel with the aperture, the coupling field is the sum of the lower-frequency components with the sources´ characteristics and the higher-frequency resonance fields of the cavity