Apertures and slots of the enclosures come into prominence for heat allocation, ventilation, I/O cable, etc. These slots and apertures induce the coupling route of electromagnetic interference (EMI) from the inside to outside. So, electromagnetic shielding is usually used to decrease the emissions or to the progress of equipment immunity. In this paper, an effect of an aperture shape on the performance of electrical shielding effectiveness has been investigated by means of simulation. Rectangular, square, circular, equilateral triangle and hexagonal shape apertures that have a constant area of 5625 mm² have been studied in addition to polarization type of applied electromagnetic field. It has been observed that ESE depends on the electric field direction and plane wave polarization and rectangular shape aperture has more effective ESE performance than square, circular, equilateral triangle and hexagonal type apertures. Rectangular shaped aperture has approximately 43 dB better performance than equilateral triangle one for whole frequency band of 100 MHz to 1GHz. Rectangular, square, circular, hexagonal and equilateral triangle type apertures have been ranked from best performance to the worst with respect to their ESE. There have been considerable findings that can be useful for enclosure designers about the effect of angle of incidence and polarization angle.

A mathematical model based on both frequency and relative water content of two tropical crops’ ‘rubber and magnolia’ leaves derived from measurements has been proposed in the frequency range of 3—7 GHz. Leaf samples sandwiched with Plexiglas side holders are inserted within waveguide sections, and the dielectric constants are calculated from the complex transmission coefficient S₂₁. In general, complex dielectric constant of materials (leaves in this case) is a function of frequency and water content. A model obtained from the data of rubber based on both frequency and relative water content is compared with the models in the literature and verified by measurements of control samples (magnolia in this case). From the comparisons, it is observed that proposed model has been found to show more promise in prediction of the dielectric constants, and model has, at most, ±10% error in relative dielectric constant ( ) in broad band measurements. Relative dielectric constant is decaying by ∼ and shifts down by relative moisture constant by ∼ .

Electromagnetic shielding has become more important in recent years as a result of increased electromagnetic environment pollution, its long-term health effects and information security in buildings. Therefore, the studies on building materials that can prevent electromagnetic emission have caused great attention. Additionally, accurate measurements of electrical characteristics properties of materials can provide scientists and engineers with valuable information to properly incorporate the material into its intended application for more solid designs or to monitor a manufacturing process for improved quality control. This paper mainly focused on the progress and prospective future of cementitious building materials by using waste metallic chips as a constituent for the purpose of electromagnetic shielding, wave absorbing activities and electrical properties of materials. For this purpose, natural sand was replaced in volume provided from different industrial areas in the production of cementitious composite, and these materials were examined to determine their electromagnetic shielding, absorbing capabilities and dielectrical constants. As a result, although reference sample has almost 7 dB shielding efficiency, sample having iron chips (60%) has 18 dB shielding efficiency which is known as good shielding material property value.