Compare of Shielding Effectiveness for Building Materials with Different Air Gap

摘要

During the 1990s, most electromagnetic field research focused on extremely low frequency exposures stemming from conventional power sources, such as power lines, electrical substations, or home appliances. Now, in the age of mobile telephones, wireless routers, and portable GPS devices (all known sources of EMF radiation), concerns regarding a possible connection between EMFs and adverse health effects still persist. Quality shielding materials are determined by three coefficients, shielding effectiveness SE, absorption coefficient A and a reflection coefficient R. The shielding effectiveness SE is closely related with coefficient R, and A. This paper deals with compare the shielding effectiveness of two bricks with different air gaps. The air gaps constitute 60% of Sample 1 and the air gaps constitute 80% of Sample 2. Measurements were performed in the frequency range from 1GHz to 9 GHz. Many devices that people use in dailylife and are exposed to are working in this frequency range. Measurements were performed according to the IEEE Standard, Method for Measuring the Effectiveness of Electromagnetic Shielding Enclosures. Measurements were performed in the non-reflection chamber in order to avoid the exterior influence. Measurements point to the shielding effect of building material (brick). The article also compares the shielding effectiveness of electromagnetic field for different air gaps.