INVESTIGATIONS ON MULTIBAND METAMATERIAL ANTENNA DESIGN FOR WIRELESS APPLICATIONS

Abstract

This thesis presents a few multiband antennas designed by exploiting the unique properties of metamaterials. The use of metamaterials in the design not only helps us in realizing multiband antennas but also aids in improving certain performance parameters. All the designed antennas are microstrip fed and use via less metamaterial structures. The design of these antennas is aimed at wireless applications below 6 GHz. The rapid increase in the use of wireless operating devices and their capability of handling multiple technologies has led to an increase in the demand of antennas operating at multiple frequency bands. The monopole antennas have low profile and can be easily manufactured and integrated into the devices. Hence, a proper combination of these antennas with an embedded metamaterial structures in the design is feasible for realising multiband antennas. The slots, composite right left-handed transmission line (CRLH-TL), split ring resonators (SRR), composite split ring resonators (CSRR) and meandered line structures are incorporated in the antenna design to realize the multiband antennas. Moreover, to enhance the certain performance parameters of the antenna, metasurfaces formed by artificial magnetic conductors (AMC) and perfect electric conductors (PEC) have been employed. In this thesis, the design of antennas targeted towards the WLAN, WiMAX, and sub 6 GHz 5G applications has been presented. Initially, a monopole antenna with slots etched on the radiator has been presented in chapter three. The slots are employed in the design to realise the dual band (2.38 - 2.7 GHz, and 3.28 - 5.8 GHz) nature of the antenna and it is backed by an AMC surface for enhancing the gain of 5dBi in the first band and 2.8 dBi in the second band. In chapter four, a compact antenna of the order 0.3λ0 x 0.2λ0 x 0.01λ0, dual band (3.15 - 4.09 GHz and 5.35 - 5.84 GHz) CRLH-TL metamaterial inspired design and the circuit realization of the antenna are also presented. In chapter five, a meandered line loaded dual band (3.26 – 3.61 GHz, and 5.06 – 6.77 GHz) antenna backed by a meta surface has been designed and presented with circular polarisation in one of the bands. Finally, a split ring resonator (SRR) and complementary split ring resonator (CSRR) based multi band antennas suitable for 2.5/3.5/5.5 GHz WiMAX, and 5.2/5.8 GHz WLAN applications has been presented in chapter six.