可利用注入訊號控制極化之主動圓極化天線設計

Abstract

本論文提出之圓極化主動天線，包含四個串接之雙埠隙孔耦合微帶天線，亦為一回授振盪電路。將這四個微帶天線安排成可輻射兩個正交之線性極化電場。當此主動天線振盪在某些特殊頻率時，這一對線性極化電場恰以90°相位差被輻射出去。左旋圓極化和右旋圓極化分別對應到9.62 GHz和10.36 GHz的振盪頻率。注入訊號鎖定振盪器於對應的頻率，可獲得所需要的圓極化。我們以精確的方式模擬此主動天線，並將之實現。此外，還實際測量出其輻射之頻譜與場型，並且與模擬結果比較。我們得知，當此主動天線輻射左旋(右旋)圓極化電場時，其等效輻射強度為23.06 (26.75) dBm，而其品質因素為230 (228)。

In this thesis, the proposed circularly polarized active antenna containing four serially connected two-port slot-coupled microstrip antennas performs as an oscillator. The patches of this active antenna are arranged to radiate two orthogonal linearly polarized fields. These two field components can be radiated with 90° phase differential as the active antenna oscillates at particular frequencies. The left-hand and right-hand circular polarizations correspond to 9.62 GHz and 10.36 GHz oscillation frequencies, respectively. By injecting locking signals into the oscillator, the oscillation frequencies can be selected to generate needed circular polarization. The active antenna has been simulated with accurate approaches and been implemented. In addition, the radiation spectra and patterns have been measured and compared with the simulated ones. As LHCP (RHCP) is selected, the EIRP of the active antenna is 23.06 (26.75) dBm, and the external Q-factor is 230 (228).