Time Domain Analysis of the Effect of Apertures on the Shielding Effectiveness of Buildings

High intensity electric and magnetic fields produced by lightning discharge can penetrate through any structure in its vicinity. Installation of a sensitive component inside any structure complying the Electromagnetic Compatibility standards need the information of exposure limit of the equipment in the installation environment. Any structure provides natural shielding to electromagnetic field and its limit depends on the material properties. In addition the structure dimension plays key role in defining the limit of shielding. This paper investigates the effect of aperture on the shielding effectiveness of building structure made of construction material against lightning electromagnetic fields. Building structures constructed in computer aided design (CAD) tool, are subjected to lighting electromagnetic field in FEKO Electromagnetic simulation software. Time domain approach is used to compute the shielding effectives of the building for different structural variations. It is seen that apertures decrease the shielding effectiveness of the building . As the structure size increases the percentage decrease in shielding effectiveness due to the presence of aperture increases. For magnetic field, construction material does not provide considerable shielding.