Study of Ultra Wide Band Antennas for Future Wireless Communication Devices

Abstract

The current work provides a detailed analysis of ultrawideband antennas, exploring their various crucial features such as broad band impedance matching, rejection for interfering wireless bands and optimum gain and bandwidth values utilizing novel metamaterial structures. It has been observed from the literature study that as a UWB antenna covers large unlicensed band from 3.1 to 10.6 GHz, therefore it needs to have consistent or stable performance in the entre working bandwidth. It led to the utilization of a broadband impedance matching technique called distributed impedance matching method to obtain satisfactory matching properties in the present work. Along with proper impedance matching, the second important requirement of an UWB antenna is to have good notching characteristics. The method of attaching tuning metallic stubs/strips to antenna structure is presented in this thesis. It is one of the simplest rejection techniques which mainly alters the surface current distribution and provides high impedance at notched frequencies. Now another crucial need of UWB antenna is to have optimal gain and bandwidth values. For this purpose, we designed various novel shaped metamaterial unit cells and then utilized them as a reflector plane along with the designed UWB antennas. As the study of metamaterials have gained huge attention now a days, hence detailed analysis of these unit cells including their complete structural progression, electric and magnetic field distribution, bending analysis, extraction of material properties along with circuital analysis is performed. Further the double negative metamaterials are considered one of the most important members amongst the metamaterial family due to its vast applicability in various fields, hence it is focused more in this work. Further two flexible metamaterial antennas designed gave satisfactory outcomes in terms of their gain, bandwidth and forward radiation characteristics. All the proposed antennas and metamaterial cells have novel structures and gave better outcomes when compared with the latest existing designs.