本論文設計了頻率可重置性的雙頻段天線，操作頻帶分別是全球定位系統GPS頻段(1.227 GHz~1.575 GHz)，以及雷達波段S頻段(2.45 GHz)。天線結構主要是以帶狀線作為輻射體，以電感性饋入加上電容器元件來產生共振模態，改變電容器容值可調整天線中心頻率，還能有效縮小天線面積。 首先從單頻天線的結構開始設計，利用相同的共振機制發展雙頻與多頻天線，經過適當設計把頻率相近的兩個共振點結合成一個寬頻響應，將S頻段(2.45 GHz)的頻寬從120 MHz增加至205 MHz，提升了70%頻寬，以廣泛應用在衛星、雷達通訊裝置。 將電容器替換成可變電容，加入偏壓電路施以直流偏壓作為調頻結構。可在S頻段(2.45 GHz)不被影響的情況下，在GPS的L1、L2及L3頻段(1.227 GHz、1.381 GHz及1.575 GHz)之間切換，達到頻率可重置性天線的設計。最後透過實作跟量測來驗證模擬結果。 ;In the thesis, designs of a dual-band frequency reconfigurable antenna which covers the GPS band (1.227 GHz ~ 1.575 GHz) for Global Positioning System applications and the S band (2.45 GHz) for radar system applications are presented. Striplines are mainly used in the antenna structure as radiators. Inductive feed is used with the capacitor elements to generate resonant modes. By changing the value of the capacitor, the antenna center frequency can be adjusted, and the antenna size can be reduced. We first design the single-frequency antenna structure. We then use the same resonance mechanism to develop dual-frequency and multi-frequency antennas. The similar frequencies of the two resonant modes are combined into a broadband response by an appropriate design. The S-band (2.45 GHz) bandwidth is increased from 120 MHz to 205 MHz. We later replace the capacitor with a variable capacitor, and apply the bias circuit to give the DC voltage as the tunable structure. The dual-band frequency reconfigurable antenna can be switched between the GPS L1, L2 and L3 bands (1.227 GHz, 1.381 GHz and 1.575 GHz). In the case, the performance of the S band (2.45 GHz) is not affected. Finally, through the implementation and measurement the proposed designs are all validated.
