在這篇論文中主要是探討使用寄生元件之平面式倒F型雙頻天線(Dual-band Planar Inverted-F Antennas with a Parasitic Element)之設計，藉由外加寄生元件來修正其阻抗匹配與增加頻寬。本論文以操作頻帶為IEEE 802.11.a/b/g (WLAN)、802.16 (WiMAX)、藍芽(Bluetooth)之天線為實例進行設計，涵蓋2400~ 2484 MHz以及5150~ 5825 MHz。首先依照天線理論估算出天線共振頻率之電流路徑長度，並選擇適當阻抗的饋入點位置，再由FR4之所製的50歐姆微帶線饋入天線主體，並且以全波電磁模擬軟體Ansoft HFSS Version 10.0進行模擬、反覆驗證設計平面式倒F型雙頻天線，不但有一個較低頻的2.4 GHz頻帶產生，而且還有一個較高頻的5 GHz頻帶在此天線中形成響應。另外再增加一寄生元件使得高頻部分之頻寬增加，同樣以模擬軟體調整天線尺寸執行最佳化設計。在實際製作方面，使用厚度為0.3 mm的銅片製作天線主體與寄生元件，尺寸為10 8 4 mm ，以及介質常數為4.4的FR4印刷電路板製作微帶線基底，尺寸為50 30 0.8 mm ，訊號經過微帶線饋入至天線主體中，接著量測天線之阻抗頻寬、輻射埸型、天線增益等相關參數。最後，比對天線之模擬與量測相關數據可得到相當一致性之結果，操作頻帶可完全涵蓋2400~2484 MHz與5150~5825 MHz，得證此雙頻天線設計。 The design of dual-band planar inverted-F antennas with a parasitic element modifying impedance matching and broadening bandwidth are discussed in this thesis. The proposed antennas are designed for IEEE 802.11.a/b/g (WLAN), 802.16 (WiMAX) and Bluetooth covering 2400~2484 MHz /5150~5825 MHz. First of all, we estimated the distance of current path according to antenna theory at resonant frequencies, and determined appropriate position of fed point to meet impedance matching, then fed into radiation element through 50 Ohm microstrip line. We simulated the dual-band PIFAs without parasitic element using full-wave electromagnetic simulation soft Ansoft HFSS Version 10.0 to design and verify it reiteratively, and achieved not only a lower band (2.4 GHz) but also an upper band (5 GHz) of 2nd mode resonance in this response. Especially, adding an extra parasitic element to broaden impedance bandwidth of upper band is applied, then simulated it using HFSS for optimum dimensions of proposed antennas as well. For implementing the antennas, we designed a substrate of 50 Ohm microstrip line made of FR4 printed circuit board with =4.4 by 50 30 0.8 mm , and both the radiation and parasitic element are made of copper patches of 0.3 mm thickness by 10 8 4 mm . The RF signal is fed into the PIFAs via 50 Ohm microstrip line for measuring impedance bandwidth, radiation patterns, gain … etc. Finally, we achieved the consistency result after comparing these parameters about simulations and measurement. The design of antennas is proved.
