Hollow pyramidal in plastic composite brick / Nurul Athirah Imam

The rapid growth of wireless technologies, including 5G, mobile communication systems, and Wi-Fi, has resulted in increased electromagnetic wave (EMW) emissions, raising concerns over their impact on communication systems, electronic devices, and human health. The need for efficient and sustainable EMW absorbers has become critical, especially in addressing environmental health concerns. This study aims to design and develop plastic composite bricks with surface modifications using Palm Oil Fuel Ash (POFA) and PET, analysing their EMW absorption performance across frequencies of 1 GHz to 12 GHz. The methodology involved resistivity and dielectric testing, simulations using CST software, and validation through the NRL Arch Measurement setup. Results indicate that surface modifications enhance EMW absorption significantly. SM1, with a single large pyramidal surface, excelled in the X- band, optimized for high-frequency absorption, while SM2, featuring an array of smaller pyramids, exhibited consistent broadband performance across the L-, S-, and C- bands. Horizontal orientation produced results aligned with theoretical predictions, while vertical orientation showed some inconsistencies, likely due to partial obstruction of the hollow structure. Performance decreased at steeper angles, with 60° showing reduced interaction with the modified surfaces. These findings underscore the potential of surface-modified plastic composite bricks as versatile EMW absorbers, suitable for applications in communication and shielding technologies, while highlighting opportunities for further enhancements in design and frequency range coverage.