本研究之主旨為研製新型自振式環型主動集成天線，並達到小型化及可頻率重置之效果。此研究將微波電晶體直接嵌入環型微帶天線之內部，使天線不僅為輻射體，亦作為振盪器之迴授路徑。此一體化結構，可有效縮小電路面積、降低線路傳輸損失，並可透過迴授路徑獲得良好之相位雜訊。
本論文首先提出一款具迴授路徑之自振式環型主動天線；其次，將相同尺寸之環型天線一側邊開路，成功完成前款設計之小型化實現，其電路具有50%之縮小比例。兩款天線的振盪器指標(FOM)分別為為-177.07 dBc/H及-168.76 dBc/Hz。
本論文之第二部份，則於環型天線引入間隙負載，使其具有多模態操作之特點，並用於兩款新型自振式主動天線設計。該兩款設計使用相同尺寸之環型天線，但利用不同位置之間隙負載，可使振盪頻率分別為3.65 GHz及5.65 GHz，其振盪器指標則為-163.08 dBc/Hz及-171.02 dBc/Hz。
最終，本論文利用PIN二極體控制間隙負載之開路或短路，成功實現一款可頻率重置自振式主動天線。該天線可操作於兩振盪頻率，其振盪器指標分別為-170.73 dBc/H及-162.62 dBc/Hz。
參酌文獻記載，可知本論文所提出之五款新型主動天線設計，具有小型化之優勢，且有相當之振盪器指標。

This study focuses on the development of novel self-oscillating annular ring active integrated antennas (AIAs) with compact size and reconfigurability. The annular ring microstrip antenna, with a microwave transistor being directly embedded into its structure, acts not only a radiator but a feedback loop of the oscillator. Due to the integration, the proposed design can significantly reduce the circuit size, lower the transmission loss, and obtain better phase noise with the feedback.
A self-oscillating annular ring active integrated antenna with feedback loop is first proposed. A compact version of the first design, with a size reduction percentage of 50%, is then realized by modifying the boundary condition of the radiator such that the antenna resonance is changed from one-wavelength mode to a half-wavelength mode. According to the experiments, the oscillator figure of merits (FOMs) of the two designs are, respectively, -177.07 and -168.76 dBc/Hz.
By introducing a gap loading, the annular ring microstrip antenna exhibits mulit-mode operation, which can be utilized to develop two novel self-oscillating active antennas. The new designs, oscillating at 3.65 and 5.65 GHz, respectively, use the same radiator but difference gap loading. The oscillator FOMs of the two designs are -163.08 and -171.02 dBc/Hz, respectively.
Finally, by utilizing PIN diodes to control the location of the gap loading, a frequency-reconfigurable self-oscillating active antenna is successfully implemented. The antenna can switch in two oscillating modes, with oscillating frequency of 3.45 and 5.25 GHz. The oscillator FOMs are -170.73 and -162.62 dBc/Hz, respectively, for the two modes.
When compared with the designs in literature, the proposed self-oscillating active antennas in thesis feature more compact size with compared oscillator FOMs.

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