Research, Designs And Fabrications On Novel Ultra-wideband Antennas

With the development of ultra-wideband communication systems, it sparks great interests on the designs of ultra-wideband antennas, one of the most important components of the whole system. Basically, the ultra-wideband antennas should be low-profile, compact, light weight and easy to integrate with printed circuite board. The aim of the thesis is to design different kinds of antennas that meet the requirements of ultra-wideband systems and discuss varied approaches to improve the performance or decrease the size of the antennas.First, we briefly introduce the ultra-wideband technology and some basic design parameters of the ultra-wideband antennas, and then retrospect the history of the development of wideband / ultra-wideband antennas. Second, we talk about a few numerical methods that are used in the design process of the ultra-wideband antennas, mainly discussing Finite Element Method (FEM) and Finite Integration Technology (FIT).After that, we focus on the designs and calculations of the ultra-wideband monopole antennas in order to figure out ways to improve the performance of the antennas. In this part, we start from the planar monopole antennas, discussing its working principles, basic structures, and present a few design examples which meet the basic requirements of the ultra-wideband system. Then, in order to reduce the bulky size of the planar monopole antennas, we propose the printed monopole antennas, which are low- profile, compact size, and easy to integrate with printed circuit board while working in ultra-wide frequency bands. Finally, we design a few ultra-wideband antennas with multiple band-notched characteristics to avoid adjacent interferences by combining the novel meta-materials with printed monopole antennas.In the last part, we conclude the thesis and make several suggestions for the future work.