Design and Development of Radio Wave Absorber Using Eco-Friendly Materials

Abstract

An investigation on using eco-friendly natural materials like coconut pith, rubber, and charcoal powder for developing radio wave absorbers has been reported in this paper. Two absorbers named CoR (Combination of Coconut pith powder and natural Rubber latex) and CoRC (Combination of Coconut pith powder, natural Rubber latex, and Charcoal powder) are made through proper mixing and drying. The absorptivity of these two absorbers (CoR and CoRC) is compared with the industrial standard polyurethane based absorber. The waveguide method is employed to measure the absorptivity of these absorbers in 3 different frequency bands. Band 1 (1.7-2.6 GHz) includes the mobile communication frequencies of 1.8 GHz and 2.4 GHz. Band 2 (4.9-7.05 GHz) is intended for sub 6 GHz band of 5G as well as WLAN frequencies while band 3 (8.2-12 GHz) is for higher frequencies of radar operation. The exact values of lower and upper frequencies of bands are determined by the physical dimensions of waveguides used. The absorption capability of the absorbers is found to increase as the frequency of operation increases. The CoR absorber has almost 63% average absorptivity in band 3, 56% in band 2, and 21% in band 1. The CoRC absorber has an average of 74% absorptivity in band 3, 63% in band 2, and 24% in band 1. Recently, many researchers have shown keen interest in developing radio wave absorbers from natural materials. This is due to the widespread requirement of absorbers for military, medical, and research purposes. Simón et al. in [10] have investigated the suitability of using powdered coir for microwave absorption application. The capability of microwave absorption is discussed in terms of its transmission characteristics (S 21) using the waveguide method in X band. A more comprehensive