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International Journal of Antennas and Propagation
Volume 2014 (2014), Article ID 498767, 9 pages
Research Article

A Study of the Anechoic Performance of Rice Husk-Based, Geometrically Tapered, Hollow Absorbers

1School of Computer & Communication Engineering, Universiti Malaysia Perlis (UniMAP), Pauh Putra Campus, Arau, 02600 Perlis, Malaysia
2School of Electrical System Engineering, Universiti Malaysia Perlis (UniMAP), Pauh Putra Campus, Arau, 02600 Perlis, Malaysia

Received 29 August 2013; Accepted 25 November 2013; Published 5 January 2014

Academic Editor: Ananda Sanagavarapu Mohan

Copyright © 2014 Muhammad Nadeem Iqbal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Although solid, geometrically tapered microwave absorbers are preferred due to their better performance, they are bulky and must have a thickness on the order of λ or more. The goal of this study was to design lightweight absorbers that can reduce the electromagnetic reflections to less than −10 dB. We used a very simple approach; two waste materials, that is, rice husks and tire dust in powder form, were used to fabricate two independent samples. We measured and used their dielectric properties to determine and compare the propagation constants and quarter-wave thickness. The quarter-wave thickness for the tire dust was 3 mm less than that of the rice husk material, but we preferred the rice-husk material. This preference was based on the fact that our goal was to achieve minimum backward reflections, and the rice-husk material, with its low dielectric constant, high loss factor, large attenuation per unit length, and ease of fabrication, provided a better opportunity to achieve that goal. The performance of the absorbers was found to be better (lower) than −20 dB, and comparison of the results proved that the hollow design with 58% less weight was a good alternative to the use of solid absorbers.