Shielding Characterization of Metallic Enclosures With Multiple Slots and a Thin-Wire Antenna Loaded: Multiple Oblique EMP Incidences With Arbitrary Polarizations

Shielding effectiveness (SE) of metallic rectangular enclosures with thin slots and a thin-wire antenna loaded by an impedance, illuminated by multiple electromagnetic pulses (EMPs) simultaneously, is investigated using a hybrid finite-difference time-domain (FDTD) method. In order to enhance the simulation efficiency of the FDTD algorithm, accurate formulas for handling multiple thin slots, a thin-wire antenna, and a lumped network are integrated together. Numerical results show that for real metallic enclosures, their shielding performance is very sensitive to the variations in direction and polarization angle of the incident EMPs. However, at a given frequency, the resistance and inductance loaded at the terminal of a thin-wire antenna have little effect on the SE level. For two, three, as well as more EMP incidences, common-frequency interferences will result in strong inner field resonance in the enclosure.