本論文研製一個具有2.4GHz頻帶圓盤型雙偶極天線的改良，利用Yagi(八木天線)的原理讓天線產生具有方向性波束(Directional Beam)，分別研製水平四根擺放負責水平極化四個象限，以及垂直四根擺放負責垂直極化四個象限，進而去組合而成一個垂直跟水平共八個象限的類似圓極化天線，使它可涵蓋各個方向的覆蓋率，可滿足智慧型天線系統的應用。這是一種原理簡單、製作容易、成本低廉，利用電子業常廣泛應用的印刷電路板去結合而成的天線，天線本體總共有三片PCB去組合而成的圓盤天線，具有組裝跟生產容易，體積為88.44 × 88.44 × 41.6 mm3。詳細的天線設計及實驗數據將在本論文中說明及討論。;This thesis is the implementation of a modified dipole antenna designed on circular disk at frequency 2.4GHz band. By using the principle of Yagi antenna, the directional beam is generated. Four antennas were developed to cover four quadrants at horizontal polarization, and another four antennas were developed to cover four quadrants at vertical polarization. They could be combined into an antenna with a total of eight quadrants radiation pattern including vertical and horizontal polarization similar to circularly polarized antenna. It covers all directions to meet the application of Smart Antenna System. This is a simple, easy-making, low-cost method to use printed circuit board for this implementation. The circular Yagi antenna assembled with three PCBs and the size is about 88.44 × 88.44 × 41.6 mm3. Detail content of the antenna design and experiment result is discussed in this paper.