本論文提出兩種高頻液晶帶線天線之設計，其中第一種為應用於Ka-band之雙頻液晶帶線天線，此設計透過在結構中結合向列型液晶材料，藉由控制電壓以改變液晶材料之介電常數與介電損耗，進而達到調整工作頻率之效能。此外，此天線還同時結合了堆疊(stack)與帶線(strip line)結構來增加天線頻寬與天線增益。由模擬結果得知，此天線在施予亦經偏壓前的中心操作頻率分別為25.08 GHz與29.22 GHz，而在施予液晶偏壓後的中心操作頻率則分別為24.43 GHz與28.62 GHz，這兩個中心操作頻率分別偏移了2.63%與2.1%，而天線增益則為5.57 dBi。第二種為應用於Ku-band且具有高通帶覆蓋率之雙頻液晶帶線天線設計，此天線之結構同樣結合了液晶材料、堆疊結構與帶線結構，此外還透過優化的參數設計使此天線具有高通帶覆蓋率之效能。由模擬結果得知此天線在施予液晶偏壓前的中心操作頻率分別為16.56 GHz與18.76 GHz，而在施予液晶偏壓後的中心操作頻率則分別為16.12 GHz與18.28 GHz，中心操作頻率分別偏移了2.65%與2.55%，通帶覆蓋率為61%，天線最大增益為4.376 dBi。而實際量測之結果則顯示在液晶材料尚未施予偏壓時的中心操作頻率分別為16.4 GHz與19.48 GHz，而在液晶施予偏壓後的中心操作頻率則分別為16.08 GHz與19.24 GHz，中心操作頻率分別偏移了約1.95%與1.23%，整體頻段覆蓋率為60.98%。此外本設計天線之中心工作頻率在液晶偏壓前，量測數值與模擬結果之偏差量分別為0.96%與3.8%。而在液晶偏壓後，量測與模擬結果之中心頻率偏差量分別為0.24%與5.2%。這些頻率偏差主要是由製程時的公差所導致，但整體量測結果大致與模擬結果相符合。

In this thesis, two kinds of stripline patch antenna designs based on liquid crystal(LC) material have been presented. In the first case, a novel design of reconfigurable dual-band stripline patch antenna using nematic LC materials, which resonates at Ka-band frequency is reported. The reconfigurability was achieved by altering the dielectric anisotropy of LC materials. In addition, this design also combines stack and stripline structures to increase the bandwidth and gain of the antenna. Full-wave simulations have shown that the operating frequencies of the antenna were 25.08 GHz and 29.22 GHz respectively before applying a bias voltage to the LC materials, and 24.43 GHz and 28.62 GHz respectively after applying a bias voltage to the LC materials. The frequency tunability range is 2.63% and 2.1% respectively and the antenna gain is 5.57 dBi.
In the second case, an experimental investigation of a dual-band stripline antenna, which resonates at Ku-band frequency is reported. The fundamental structure of this design is similar to case 1. According to the simulation results, the operating frequencies of the antenna were 16.56 GHz and 18.76 GHz respectively when the LC materials are unbiased, and 16.12 GHz and 18.28 GHz respectively when the LC materials are biased. The frequency tunability range is 2.65% and 2.55% and the antenna gain is 4.376 dBi; the passband coverage rate is 61%. The measurement results show that the operating frequencies of the antenna were 16.40 GHz and 19.48 GHz respectively without applying a bias voltage to the LC materials, and 16.08 GHz and 19.24 GHz respectively after applying a bias voltage to the LC materials. The frequency tunability range is 1.95% and 1.23%, the passband coverage rate is 60.98%. Moreover, the frequency deviations were only 0.96% and 3.8% / 0.24% and 5.2% with/without a bias voltage to shift the center frequencies. These experimental results have further verified the numerical simulation despite the frequencies deviations resulting from the fabrication tolerances.
In this thesis, two kinds of stripline patch antenna designs based on liquid crystal(LC) material have been presented. In the first case, a novel design of reconfigurable dual-band stripline patch antenna using nematic LC materials, which resonates at Ka-band frequency is reported. The reconfigurability was achieved by altering the dielectric anisotropy of LC materials. In addition, this design also combines stack and stripline structures to increase the bandwidth and gain of the antenna. Full-wave simulations have shown that the operating frequencies of the antenna were 25.08 GHz and 29.22 GHz respectively before applying a bias voltage to the LC materials, and 24.43 GHz and 28.62 GHz respectively after applying a bias voltage to the LC materials. The frequency tunability range is 2.63% and 2.1% respectively and the antenna gain is 5.57 dBi.
In the second case, an experimental investigation of a dual-band stripline antenna, which resonates at Ku-band frequency is reported. The fundamental structure of this design is similar to case 1. According to the simulation results, the operating frequencies of the antenna were 16.56 GHz and 18.76 GHz respectively when the LC materials are unbiased, and 16.12 GHz and 18.28 GHz respectively when the LC materials are biased. The frequency tunability range is 2.65% and 2.55% and the antenna gain is 4.376 dBi; the passband coverage rate is 61%. The measurement results show that the operating frequencies of the antenna were 16.40 GHz and 19.48 GHz respectively without applying a bias voltage to the LC materials, and 16.08 GHz and 19.24 GHz respectively after applying a bias voltage to the LC materials. The frequency tunability range is 1.95% and 1.23%, the passband coverage rate is 60.98%. Moreover, the frequency deviations were only 0.96% and 3.8% / 0.24% and 5.2% with/without a bias voltage to shift the center frequencies. These experimental results have further verified the numerical simulation despite the frequencies deviations resulting from the fabrication tolerances.

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