Analysis And Design Of Band-Notched Ultra Wideband(UWB) Antennas

Ultra-wideband (UWB) antenna techniques applied in the emerging UWB wireless communication systems are studied. With the rapid development of the UWB technology, especially after the U.S Federal Communication Commission (FCC) authorized the unlicensed use of UWB (3.1GHz-10.6GHz) in February 2002, the demands of UWB antenna increase quickly. The antennas with characteristics of complanation, miniaturization and intelligentize have become a hot topic in telecommunication industry. The antennas in this dissertation also have the characteristics mentioned above.In this dissertation, a survey on the ultra wide-band antenna is presented. The performance parameters, common structures, band-notched characteristics and analysis methods are discussed. Based on the research, two UWB antennas are proposed, then analyzed by theoretical method and simulated by software HFSS.One of the proposed antennas is band-notched microstrip UWB printed monopole antenna. During research, the transmission line modeling theory and the cavity modeling theory of the microstrip patch antenna are studied first, which give the relation between the size of the microstrip patch antenna and the resonant frequency, as well as the relation between the size and the input impedance. The proposed antenna is composed of a cirque ring with a small strip bar, so that the antenna occupies about 8.29GHz bandwidth covering 3.18–11.47GHz with expected band rejection of 5.09GHz to 5.88GHz. A quasi-omnidirectional and quasi-symmetrical radiation pattern are also obtained. This kind of band-notched UWB antenna requires no external filters, and thus greatly simplifies the system design of UWB wireless communication.Another antenna which has Dual Band-Notched characteristic is Compact UWB monopole Antenna fed by coplanar waveguide (CPW). This antenna has the bandwidth from 3.01GHz to 12GHz above with dual stop bands at 3.5GHz WiMax and 5.8GHz WLAN. The dual stop bands are achieved by a simple circular slot and a compact coplanar waveguide resonant cell respectively. Accordingly, this antenna is applicable for UWB communication systems with the anti-jamming ability or low interference ability to other wireless systems.