Multi band printed antennas using meta material structures

Abstract

The upturn of wireless devices for communication has re-enthused the attention and interest in electrically small, efficient and multiband antennas. Microstrip based electrically small, efficient and multiband antennas are low-cost, easy to fabricate and are easily integrated into more advanced multifaceted systems to fulfil the requirements and needs of new generation wireless systems. Unfortunately, these requirements are incongruous with traditional electrically small antenna designs, compromises have to be done. Recent advancement in electromagnetics (novel radiating structures) in the radio frequency spectrum and novel fabrication techniques offer a large number of stimulating and exciting new applications in the field of antennas and wireless communications. These structures are called “Metamaterials” and are not found in nature but artificially engineered. These materials can help to improve and enhance the performance and characteristics of electrically small antennas because they allow for unusual electromagnetic properties. The objective of this thesis is to introduce and develop new microstrip based antenna topology with metamaterial structures that can provide better and improved performance and characteristics for wireless communication systems. The target of this thesis is to achieve multiband behaviour with the use of metamaterial structures closely placed with microstrip antennas. Such antennas are feasible for portability and capable of handling multiband wireless applications. The thesis presents design, fabrication and characterization of three dipole antennas for multiple S-band and C-band applications. These antennas are made directional using reflectors in the ground plane. The metamaterial structures and reflectors are embedded on the same plane making the overall structure of antennas compact. Gain enhancement is achieved in the S band, with four distinct resonances as a result of simultaneous excitations of different segments of the split ring resonator (SRR) metamaterial through coupling from dipole elements, by arranging the proposed Yagi antenna in array of two elements using Wilkinson power divider. Measured results of all the designed prototype antennas are reported. Simulation and measured results confirm our premise.