||In recent years, the development of wireless communication systems has grown rapidly. The existing spectrum is gradually becoming insufficient. In order to further increase the data transmission rate, utilize the spectrum effectively, and improve the security of communications, radio of higher frequencies can be used. Therefore, higher frequency communication becomes more popular. This results in more and more millimeter wave applications. Because of the short transmission distance of millimeter wave, a high gain antenna is required to overcome this problem. In this thesis, we propose high directivity and high gain antenna arrays which cover the whole unlicensed band.|
In this thesis, we also propose a wideband and high directivity antenna with end-fire radiation. After designing two different structures of Yagi antennas, we accomplish two kinds of 1×4 Yagi antenna arrays to enhance the gain. One antenna type is the Yagi antenna which consists of the typical balun, for the differential feed; the other type is the antenna which has a miniature balun structure and uses three drivers to construct the quasi-Yagi antenna. In this thesis, both of the 1×4 Yagi antenna arrays have a bandwidth of more than 10 GHz. Moreover, one of the 1×4 Yagi antenna array achieves a gain of 14.3 dBi, the other achieves a gain of 15 dBi. In order to reduce the cost and expand its applications in products, we can base our design on the 1×4 Yagi antenna array structure to derive the 2×4 Yagi antenna array.