This paper presents the electromagnetic wave (EW) absorption properties in terms of complex permittivity and permeability of novel green composites coconut fiber coir and charcoal powder materials. The samples were fabricated using the raw agricultural waste coconut fiber coir, charcoal powder, epoxy resin and hardener with varied composition. The dielectric properties of the materials were characterized using two-port waveguide measurement method over the X-band frequency (8.2 -12.4GHz). The average permittivity value measured is approximately 3.00 with 10wt% charcoal has the highest permittivity of 3.59. Apart from that, all samples exhibit good reflection loss of better than -25dB which means more than 99% absorption rate. The result shows the composite material is a promising organic material for electromagnetic absorber applications.

Abstract. Nowadays, most people rely on the electronic devices for work, communicating with friends and family, school and personal enjoyment. As a result, more new equipment or devices operates in higher frequency were rapidly developed to accommodate the consumers need. However, the demand of using wireless technology and higher frequency in new devices also brings the need to shield the unwanted electromagnetic signals from those devices for both proper operation and human health concerns. This paper highlights the potential of nanocellulose for electromagnetic shielding using the organic environmental nanocellulose composite materials. In addition, the theory of electromagnetic shielding and recent development of green and organic material in electromagnetic shielding application has also been reviewed in this paper. The use of the natural fibers which is nanocelllose instead of traditional reinforcement materials provides several advantages including the natural fibers are renewable, abundant and low cost. Furthermore, added with other advantages such as lightweight and high electromagnetic shielding ability, nanocellulose has a great potential as an alternative material for electromagnetic shielding application.

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 stateof-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. INDEX TERMS Electromagnetic, microwave absorber, nanocomposites, metamaterial, nanocellulose. I. INTRODUCTION In recent years, the development of wireless technologies with the particular aim at achieving higher communication throughput and wider bandwidths for high-speed communication have been developed rapidly to accommodate consumers' needs. However, the wide use of wireless communication systems has also resulted in an increasing electromagnetic interference (EMI) to the environment. The conducted or radiated electromagnetic signals interferes with The associate editor coordinating the review of this manuscript and approving it for publication was Kuang Zhang.

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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.