On The Compact Broadband Antennas And Koch Fractal Antennas

The research works are made with scientific projects. The major works can be divided into two parts:the engineering samples of two compact broadband antennas work at two different frequences are made in the first part and the measured results show good agreement with the requirements, the antennas have been applied to practical application and achieved a good use effect; and in the second part, two engineering models of Koch fractal monopole antennas suit for UWB and WLAN/WiMAX applications are proposed and the measured results indicate the antennas are suitable for broadband wireless communication application.The main research works of this thesis are as following:Firstly, with the project requirements of compact broadband UHF antenna, the definition of the UHF antenna are illustrated, the research status and the history of the UHF antenna are presented, and the design methods of the UHF antenna are discussed. The antennas are simulated by Ansoft HFSS. On the basis of the simulation, the prototype of antennas are fabricated and measured. The measured results show that the two designed antennas can obtain favorable VSWR and omnidirectional radiation characteristics in azimuth plane; what’s more, they achieved8%impedance bandwith. Therefore, it is available for this design to be applied in engineering.Secondly, to study the effect of Koch fractal boundary on monopole antenna, two Koch fractal monopole antennas for different applications are designed. The antennas are simulated by Ansoft HFSS. On the basis of the simulation, the prototype of antennas are fabricated and measured. According to the measured results, the Koch fractal boundary can reduce the antenna size effectively, and the proposed two antennas are suitable for UWB and WLAN/WiMAX applications.