Executive Summary : | The proposed project aims to limit the power level of high electromagnetic radiation used in wireless communication applications, particularly in high-rise buildings. The radiation from cell towers has a maximum power level in 50-300 meters, which can have detrimental effects on health, especially for children and elderly individuals. To address this issue, the project proposes the design of screens based on Frequency selective surfaces (Fss) that can reduce the radiation power level to a threshold value for successful signal processing without disruption of communication links. Fss structures can be designed on planar or curved surfaces and can be used as screens in windows of rooms in high-rise buildings exposed to higher radiation. The work involves designing patch and aperture type Fss structures with single or multi-layered arrangements on transparent acrylic substrates to reduce the power level of downlink GsM band frequency signals while maintaining the power level of uplink signals. Various unit cell shapes are chosen to achieve appropriate resonating frequency, bandwidth, and polarization. Prototypes of simulated Fss structures are tested using microwave signal generators and Horn antennas. Transmission coefficient, reflection coefficient, shielding effectiveness, resonating frequency, and bandwidth are measured through experimentation, and the transmission power level is adjusted based on changes in unit cell dimension, periodicity, and use of multiple layers of Fss. The project's significance lies in saving people from radiation hazards living in higher floors of buildings close to cell towers, particularly children and elderly individuals, by reducing unwanted excess radiation. An extension of the research could also involve RF energy harvesting to reduce radiation unused for mobile communication. |