A Multiband Quasi-Yagi Antenna for WiFi/Bluetooth/WiMAX/Zigbee Applications

A multi-band quasi-Yagi antenna is proposed. The structure of the antenna has a simple feeding mechanism consists of a microstrip line and transmission line. Half of the driver and director is printed on the opposite side of the substrate to achieve a stable radiation pattern. In addition, the ground plane is modified, the upper slots were added for impedance matching, the middle slot to obtain additional resonances, the lower slots to improve the upper-frequency band radiation pattern. The antenna shows multi-band characteristic and has achieved |S
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| < -10 dB in three different frequency bands (2.35-2.65 GHz, 3.8 - 4.3 GHz, 4.95 - 5.2 GHz). These frequency bands are suitable for WiFi, Bluetooth, WiMAX, and Zigbee applications. The antenna shows a relatively flat gain (4.2-5 dBi) and a very end-fire radiation pattern in all operating frequency bands.