FDTD Analysis of Metamaterial Coated Microwave Antenna

Abstract

Due to the growth in mobile wireless systems, electrically small antennas (ESAs) which are efficient and have significant bandwidth are in great demand. But these requirements are contradictory. ESAs are known to be highly capacitive in nature. As a result of this, matching a power source to the ESA requires a matching network which increases the cost in terms of manufacturing as well as real estate. In recent years a new class of materials called metamaterials has emerged. These manmade materials with their unusual constitutive parameters possess immense potential to solve the problem of size reduction. This study seeks to validate, using Finite Difference Time Domain (FDTD) technique, a new metamaterial construct to achieve the desired objectives. FDTD code is developed for a cylindrical metamaterial wrapped around a modified biological antenna. The metamaterials are modeled using a Drude constitutive parameter model to simulate frequency dispersion. Epsilon Negative (ENG) as well as Double Negative (DNG) metamaterials are taken into consideration. Results show that the ESA using a metamaterial wraparound is found to have a quality factor lower than the theoretical Chu limit. Both ENG as well as DNG metamaterials exhibit their potential. The resonant frequency of the metamaterial antenna is reduced over the classical design while the radiation pattern of the antenna remains virtually unchanged.