Ultra-wideband Antennas Used In Modern Ultra-wideband Impulse Radio Systems

As Ultra-wideband (UWB) technology has been used for civil purpose in recent years, UWB has become one of the most competitive and promising technology in the future for its merits of high data rate, low system cost and multipath immunity compared with most narrow band systems. As the key components for effective radiating and receiving a very narrow time-domain impulse signal, the UWB antennas'performances directly affect the performances of the UWB systems, which mean the design of UWB antennas is one of the challenges of system design. Because it requires not only the antennas must have a very wide impendence bandwidth, steady-going radiation patterns, high gain in the frequency-domain performance but also make sure the transmit waveform have very low dispersion in the time-domain performance.This thesis studies the UWB antennas, which are suitable for the modern UWB impulse radio (IR) system. All the antennas'frequency-domain characteristics are analyzed and researched, as well as the time-domain characteristics.The first chapter of this thesis introduces the research background of this thesis and UWB technology, as well as several important parameters to describe the performance of antennas. The definition, historical development, particularity, research method, and time-domain characteristics of UWB antennas were described and researched in detail. At last,a brief introduction of the main work of this paper is also displayed.Chapter II introduces the design of UWB planar slot antennas. Large numbers of references have been studied before the developments of the UWB planar slot antennas were summarized. Several latest published UWB planar slot antennas were described. Then integrate the techniques, such as fan-shaped configuration, fork-shaped configuration, and rounded corners on keen vertexes. Two novel UWB planar slot antennas were designed successfully. The bandwidth of the two antennas is wider than most of the UWB planar slot antennas, which have been published.Chapter III introduces the design of UWB planar monopole antennas. Three novel UWB planar monopole antennas have been designed in this chapter. Integrate the method of half ellipse shaped feed line transition, which proposed by the author and the existing methods of defect ground plane and rounded corners on keen vertexes, one of the UWB planar monopole antennas'bandwidth is wider than most of the UWB planar monopole antennas that have been published.Chapter IV introduces the design of planar UWB band-notched antennas. In recent years, the UWB antennas with a band-notched characteristics, that were used to avoid interference between the existing wireless communication systems, such as WLAN and WiMax, have been widely study. In this chapter, the author introduced several UWB band-notch antennas, summarizing the techniques to achieve the band-notch design. The two innovative UWB band-notched antennas that designed by the author were discussed in details. One of the proposed antennas achieved four notched bands more than most of the UWB band-notched antennas, which have been published.Chapter V summarized the main work and innovation of this thesis. The intending work was also expected.