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The use of the natural materials instead of conventional materials as electromagnetic absorbers promotes environmental sustainability, cost-effectiveness, and ease of accessibility. Furthermore, these materials may also be designed as absorbers and as reinforcements in building materials in a lightweight form. The absorbing ability of composite materials can be customized based on the chosen fillers. Specifically, magnetic and dielectric fillers can be incorporated to improve the absorption of a composite material compared to traditional materials. This work aims to review recent developments of electromagnetic absorbers enabled by nanocomposites, metamaterial and metasurface-based, as well as green composite alternatives. First, the background concepts of electromagnetic wave absorption and reflection will be presented, followed by the assessment techniques in determining electromagnetic properties of absorbing materials. Next, the state-of-the-art absorbers utilizing different materials will be presented and their performances are compared. This review concludes with a special focus on the future perspective of the potential of metamaterial based nanocellulose composites as ultrathin and broadband electromagnetic absorbers.

This paper presents the investigation influence of the common metallic loop like accessory on Specific Absorption Rate (SAR) averaged over 10g and 1 g tissue.The simulations were made by means CST Microwave Studio software at frequencies 2.45GHz and 2.6GHz. Numerical analysis conducted using broadband textile monopole antenna (TM) with variations of orientation and distance showed that the SAR value increased when the antenna horizontally polarized.This is up to 80% more than vertically polarized TM placed closest item to 2mm.

This paper presents the new design of simple one layer ultrathin metamaterial microwave absorber using coconut coir fibre as the substrate. The metamaterial microwave absorber is composed of a periodic array of square loops and patches with circle cut out printed on a dielectric material which is coconut coir fibre backed by PEC. CST Microwave Studio software is used for the design and simulation over frequency range of X-Band and Ku-Band (8.2–18 GHz). From the simulation result, 90% absorption was achieved in the frequency range of 8.94 – 10.0 GHz (X-Band) with highest absorption of 99.7% at 9.37 GHz. Furthermore, the metamaterial microwave absorber has a total thickness of 1.6 mm which is only approximately 0.04λ at lowest frequency. The result shows that coconut coir fibre from the agricultural waste has a great potential to be developed further in electromagnetic wave applications particularly microwave absorber.

This paper presents the Specific Absorption Rates (SAR) in the human body with a monopole antenna. The distance between the antenna and the body were varied at different distances. The parameters (εr, σ) used in the human body set according to the standard tissue equivalent liquids recommended by the IEEE and FCC. The simulations were made by means of CST Microwave Studio software at frequencies of 2.45GHz .The effect of the body on the SAR calculation in the body were measured. The SAR values were recorded in term of SAR for 10g of tissue. The TM is positioned against the metallic loop-like accessory, place on the left wrist of the generic arm at a varied distance from the cylindrical phantom. Numerical analysis conducted using a broadband textile monopole antenna (TM) with variations of orientation and distance showed that SAR values increased when the TM is horizontally polarized.