Base Station Antenna Design With Left-Handed Metamaterials

Left handed materials (LHM) are artificial materials that can be designed to have special properties. Since the unit cells of Left handed materials are much smaller than a wavelength, they obtained negative permeability and permeability values that can be used to improve the performances of antennas for applications. Inspired by these Left handed materials concepts, several LHM-inspired antennas are adopted to improve various performance characteristics of several different classes of antennas.Recently, the wide impedance bandwidth, stable unidirectional radiation pattern, nearly identical E- and H-plane patterns, low back radiation and high gain are the most important requirements for producing base station antennas using for wireless communication system. Since the range of existent technologies cannot meet all these requirements, the application of the left handed materials maybe the best way to resolve the issues. This dissertation examines the use of artificial structured materials-known as left handed materials in base station antenna applications.Firstly, the use of Zero-index left handed material to improve the impedance matching and gain of magneto-electric dipole base station antenna is explored. In this work, the magneto-electric dipole base station antenna is loaded with varies array of Zero-index left handed material elements to achieve wide bandwidth and high gain is investigated。Secondly, a novel printed vertically oriented unidirectional base station antenna is proposed. The proposed antenna is composed of a T shaped dipole, an L shaped microstrip-to-stripline transition balun and a metal via hole. All of them are printed in the same dielectric substrate perpendicular to the ground. With a rectangular slot in the T shaped dipole, the antenna operates at 2.4 GHz and 3.9 GHz with an impedance bandwidth of 2.1 GHz for SWR≤2, stable gain of around 8 dB over the frequencies from 2.12GHz to 2.6GHz.At last, With the loaded of varies array of zero index-of-refraction left handed material elements on the dielectric substrate, the vertically oriented unidirectional base station antenna achieve an impedance bandwidth of 2.3GHz for SWR≤2, a high front-to-back ratio (more than 20dB) and nearly identical E-and H-plane patterns is obtained.