In this thesis, planar quasi-Yagi antennas fed by different kinds of baluns are designed for 5GHz WLAN systems including Marchand balun, via-hole fed balun, half-wavelength balun, and multisection coupled-line balun. To obtain wider bandwidth, series-fed antenna is investigated. We also present equivalent circuit model and derive design formula to obtain higher gain. They are implemented and measured at 5GHz with FR4 PCB and results show good enhancements in both bandwidth and gain.
