A theoretical investigation on the effects of rubber filler content on flexible antenna performance

Fillers are used in natural rubber to improve their mechanical and electronic properties. This paper presents a study on the effects of filler on flexible antenna performance utilizing natural rubber as their substrate. CST Microwave Studio was used to simulate three antennas resonating at 2.45 GHz with different permittivity and loss tangent (tan δ). The dielectric properties of rubber were varied through its filler content and the type of filler used in this project was carbon black. Microwave characterization of rubber and a preliminary study on its use as the substrate of a flexible antenna have been reported recently by our group. Understanding the effects of filler content on rubber properties will facilitate efforts in flexible antenna design so that practical system requirements are met. In this paper we report new advancements found in this study with respect to the effect of filler content on antenna quality factor (Q) and its consequences on bandwidth and gain. From the simulation, the bandwidths for the antennas increased with filler content while the resonant frequency can be tuned in the same manner. Therefore, we have demonstrated the possibility of controlling antenna performance by adjusting filler content.