Design and development of microwave absorber using waste materials

Abstract

Sugarcane bagasse is a potential agricultural waste to design the pyramidal microwave absorber to be used in radio frequency (RF) anechoic chamber for testing application. An RF anechoic chamber is a shielded room covered with absorbers to eliminate unwanted reflection signal. In this work, sugarcane bagasse from the sugar industry and rubber tire dust from tire wear have been used. Both of the wastes have lossy carbon contents naturally, which has made them suitable as the raw materials for the fabrication of the low cost microwave absorbers. The dielectric constant of the sugarcane bagasse had been measured using the Dielectric Probe Technique and Software of Agilent 85071E using Transmission Line Technique. Microwave absorbers are made of two main components, a filler material that does the absorption, and a material matrix to hold the filler. In dielectric materials, the most crucial properties that enable them to be applicable as microwave absorbers are the dielectric constant and the loss factor which is the dissipation of energy in the material. Generally, dielectric material absorbers are fabricated by the combination of fillers in a polymer matrix. In this work, the fillers are the agricultural waste which is sugarcane bagasse (SCB) and rubber tire dust (RTD) from tire wear whereas the polymer matrix is unsaturated Polyester Resin RP9509 (UPR) which is rigid, flexible and electromagnetically transparent polymer. In this work, the sugarcane bagasse also has been mixed with rubber tire dust (RTD) to investigate their performance. The microwave absorber using sugarcane bagasse had been designed and simulated in the CST Microwave studio software. The measurement of waveguide technique has been used to check the reflectivity performance. The microwave absorber has been investigated in microwave frequency range between 1 GHz to 18 GHz. The results show that the sugarcane bagasse has the potential used as the base material in developing the microwave absorber and can operate in that range of frequency successfully. The adding of the filler which is rubber tire dust increased the performance of the microwave absorber. These absorbers were designed on the basis of the wave attenuation and depth of penetration data and their EMC performance was evaluated in terms of bi-static reflectivity performance. The performance of the absorbers was found to be below -10 dB. The different concentration of the filler were being measured and the reflectivity was found to be better then -20 dB when the increasing value of rubber tire dust were added.