Abstract
This thesis proposed a new type of wideband dipole antenna with a wideband balun covering the bands almost from 1.7GHz to 6.2GHz. The proposed dipole antenna is fed in microstrip line and utilizes microstrip to slotline transition method to transmit power. For this dipole antenna, it can be used in all wireless network application including all WLAN and WiMAX bands. The novelty shape of this antenna is designed for more paths of current flows. The radiation patterns are approaching Omni-direction in all bands but the front end has higher gain. It is easy to fabricate because of using FR4 substrate and the gain performance of this antenna is 3.56dBi on the average. Not only design of the wideband dipole antenna is considered in this thesis, but also modification of quasi-Yagi antenna is investigated. The conventional quasi-Yagi antennas have some artifact, so attempts have been made to solve these problems by using the Chebyshev transformer and radial stub to achieve microstrip to coplanar stripline transition and to reach wideband performance. In this section，the impedance matching problems have been discussed，thus we can design antennas from two part through some conditions. The main frequency band is operating in nearby 2.45GHz that is the most popular band we use in wireless network today. With the results obtained, it is hoped that this thesis can make some contributions to the research of wireless networks.