本論文敘述由共平面波導饋入的雙頻與三頻微帶天線設計。在天線的激發部分，藉由引進了電容型耦合的共平面波導饋入結構，及適當地調整耦合開槽的長度與寬度並選取適當的饋入位置，在每一個操作頻率的阻抗匹配皆可以容易地完成。在雙頻操作方面，本論文所提出的設計是藉由在正方形微帶天線上負載一條或兩條很窄的開槽來完成。更寬的可調頻率比範圍可由改變負載開槽的寬度或所放的位置而達成。最後，一個可三頻操作的微帶天線也利用相似的負載開槽方法而實現。此外，本論文亦針對所提到的微帶天線設計和實驗結果做詳盡的描述與討論。 Dual-frequency and triple-frequency operations of coplanar waveguide (CPW) fed microstrip patch antennas are presented in this thesis. For excitation of the proposed antennas, the capacitively coupled CPW-fed structures are proposed. By properly adjusting the dimension and location of the coupled slot, impedance matching at each operating frequencies can be achieved simultaneously. For dual-frequency operation, the proposed designs are obtained by loading one or two narrow slots in the square patch. An extended tunable frequency ratio range of the two operating frequencies can be obtained by varying the widths or positions of the loaded slots. Using the similar slot-loaded approach, a triple-frequency operation can also be realized. In addition, experimental results for the proposed structures are presented and discussed.