臺灣博碩士論文加值系統

本論文的主要目標是設計一款新型寬頻帶圓極化毫米波天線陣列並可操作於第五代通訊系統(Fifth Generation New Radio, 5G NR)中的Band-n257 (26.5–29.5 GHz)、Band-n258 (24.25-27.5 GHz)與Band-n261(27.5-28.35 GHz)。論文首先提出一新型寬頻帶圓極化毫米波天線單元，提出之天線單元為一支共平面饋入之貼片天線，利用共平面末端之金屬銅柱連接L型微帶線並將能量耦合至輻射元件，再藉由擾動輻射元件平面之電流以激發圓極化輻射特性。天線單元之量測10-dB阻抗頻寬為 27.4% (22.46–29.6 GHz)，在所需之操作頻帶內(24.25-29.5 GHz)的軸比頻寬皆在3-dB以下，並且天線單元之最高增益為9.62 dBic，其天線效率皆在76%以上，為設計高增益之圓極化毫米波天線陣列立下良好的基礎。
為符合擺設於手機邊框之需求，本論文將天線單元排列成1 × 4天線陣列形式，其總體尺寸為48 mm × 7 mm × 1.575 mm (4.36 λ0 × 0.63 λ0 × 0.14 λ0 )，且兩支天線單元之間中心對中心的距離為12 mm (約為27 GHz 之 1.08 λ0)。從量測結果得知，1 × 4天線陣列之10-dB阻抗頻寬為24.7% (23.24–29.78 GHz)，天線單元間之隔離度皆大於30 dB，且在所需之操作頻帶內的軸比頻寬皆在3-dB以下。除此之外，1 × 4天線陣列之最高增益為15.2 dBic，其天線效率也皆在71%以上。從進一步的量測得知，提出之1 × 4天線陣列能在24.5 GHz、28 GHz 與 29.5 GHz時分別達到±25˚、±30˚ 與±30˚之波束掃描角度。
由於近期的5G手機毫米波天線設計傾向於1 × 5天線陣列形式，因此為了符合最新的產業界應用，本論文也將原本的1 × 4天線陣列排列成1 × 5天線陣列形式，其總體尺寸為60 mm × 7 mm × 1.575 mm (5.4 λ0 × 0.63 λ0 × 0.14 λ0 )。此時，兩支天線單元之間中心對中心的距離依舊為12 mm (約為27 GHz 之 1.08 λ0 )，雖然相較1 × 4天線陣列尺寸稍大，但1 × 5天線陣列在天線性能上有明顯的改善。從量測結果獲知，1 × 5天線陣列之10-dB阻抗頻寬為25.8% (22.88–29.66 GHz)，略微大於1 × 4天線陣列近1%，其天線單元間之隔離度也皆大於30 dB以上，並且在所需之操作頻帶內的軸比頻寬也皆在3-dB以下。相較於1 × 4天線陣列，1 × 5天線陣列之最高增益從15.2 dBic提高到17.06 dBic，其天線效率也提高4%至75%以上。雖然1 × 5天線陣列在28 GHz 與 29.5 GHz 時所量測到的波束掃描角度與1 × 4天線陣列相似(皆為±30˚)，但是在24.5 GHz時所量測到之波束掃描角度則從±25˚提升為±35˚。
為了查明提出天線單元在不同的二維陣列排列形式的天線性能，本論文接著將天線單元排列成2 × 2天線陣列形式，兩支天線單元之間中心對中心的距離縮減為10.5 mm (約為27 GHz 之 0.95 λ0)，天線總體尺寸為30 mm × 30 mm × 1.575 mm (2.72 λ0 × 2.72 λ0 × 0.14 λ0 )。從量測結果得悉，2 × 2天線陣列之10-dB阻抗頻寬為25.8% (23.12–29.96 GHz)，雖然相鄰兩天線單元間之隔離度皆大於25 dB，但還是低於前述的兩支天線陣列 (> 30 dB)。儘管如此，其在所需之操作頻帶內的軸比頻寬也皆在3-dB以下。此刻，2 × 2天線陣列之最高增益以及天線效率也稍微高於2 × 2天線陣列，分別為15.71 dBic以及74%以上。值得關注的是，提出的2 × 2天線陣列在24.5 GHz時的波束掃描角度為±30˚，剛好介於1 × 4與1 × 5天線陣列之間所偵測到的波束掃描角度，但其在28 GHz 與 29.5 GHz時的波束掃描角度確稍微降低，分別為±28˚ 與±27˚。
最後，為了更進一步證明增加天線單元之二維陣列數量可以線性增加天線陣列的天線增益，本論文則將2 × 2天線陣列展開排列成為4 × 4天線陣列形式，此刻兩天線單元之間中心對中心的距離維持在10.5 mm (約為27 GHz 之 0.95 λ0)，相鄰兩天線單元間之隔離度與2 × 2天線陣列類似，皆大於25 dB，但其總體尺寸也相對增加至50 × 50 × 1.575 mm3 (4.5 λ0 × 4.5 λ0 × 0.14 λ0 )。從量測結果知曉，4 × 4天線陣列之10-dB阻抗頻寬為25.9% (22.9–29.72 GHz)，在所需之操作頻帶內的軸比頻寬也皆在3-dB以下。相較於2 × 2天線陣列，提出的4 × 4天線陣列之最高增益為21.83 dBic，也恰好大於2 × 2天線陣列約6 dB，且4 × 4天線陣列的天線效率(73%以上)也略高於2 × 2天線陣列約2%。令人關注的是，4 × 4天線陣列在24.5 GHz、28 GHz 與 29.5 GHz時所驗證的波束掃描角度分別為±38˚、±33˚ 與±30˚，這三項頻率的掃描結果都高於 2 × 2天線陣列。因此，從上述的所有實驗結果得知，從天線單元乃至4 × 4天線陣列形式，可證明本論文所提出的天線單元可以有效的擴展與適用在5G手機以及其它需要圓極化輻射效能的大型通訊設備。

The primary objective of this thesis is to design a novel wideband circularly polarized millimeter-wave antenna array, operable within the Fifth Generation New Radio (5G NR) system, specifically covering Band-n257 (26.5–29.5 GHz), Band-n258 (24.25-27.5 GHz), and Band-n261 (27.5-28.35 GHz). Initially, the thesis introduces a new wideband circularly polarized millimeter-wave antenna element, which is a coplanar-fed patch antenna. The energy is coupled to the radiating element using a coplanar end metallic copper pillar connected to an L-shaped microstrip line. The circular polarization radiation characteristics are excited by perturbing the current on the radiation element plane. The measured 10-dB impedance bandwidth of the antenna element is 27.4% (22.46–29.6 GHz), with an axial ratio bandwidth below 3 dB within the required operating frequency band (24.25-29.5 GHz). The maximum gain of the antenna element is 9.62 dBic, and the efficiency is above 76%, laying a solid foundation for designing high-gain circularly polarized millimeter-wave antenna arrays.
To meet the installation requirements on a smartphone bezel, the thesis arranges the antenna elements into a 1 × 4 antenna array with overall dimensions of 48 mm × 7 mm × 1.575 mm (4.36 λ₀ × 0.63 λ₀ × 0.14 λ₀) and a center-to-center distance of 12 mm (approximately 1.08 λ₀ at 27 GHz) between antenna elements. The measured results show that the 10-dB impedance bandwidth of the 1 × 4 antenna array is 24.7% (23.24–29.78 GHz), with an isolation greater than 30 dB between antenna elements. The axial ratio bandwidth within the required operating frequency band is also below 3 dB. The maximum gain of the 1 × 4 antenna array is 15.2 dBic, with an efficiency above 71%. Further measurements indicate that the proposed 1 × 4 antenna array achieves beam scanning angles of ±25° at 24.5 GHz, ±30° at 28 GHz, and ±30° at 29.5 GHz.
Given the recent trend in 5G smartphone millimeter-wave antenna designs favoring 1 × 5 antenna arrays, this thesis also arranges the original 1 × 4 antenna array into a 1 × 5 configuration with overall dimensions of 60 mm × 7 mm × 1.575 mm (5.4 λ₀ × 0.63 λ₀ × 0.14 λ₀). The center-to-center distance between antenna elements remains 12 mm (approximately 1.08 λ₀ at 27 GHz). Despite the larger size compared to the 1 × 4 array, the 1 × 5 array exhibits significant performance improvements. The measured 10-dB impedance bandwidth is 25.8% (22.88–29.66 GHz), slightly higher than the 1 × 4 array by about 1%, with an isolation greater than 30 dB between antenna elements. The axial ratio bandwidth within the required operating frequency band is also below 3 dB. The maximum gain of the 1 × 5 array increases to 17.06 dBic, and the efficiency improves by 4% to above 75%. Although the beam scanning angles at 28 GHz and 29.5 GHz are similar to those of the 1 × 4 array (both ±30°), the beam scanning angle at 24.5 GHz improves from ±25° to ±35°.
To investigate the performance of the proposed antenna element in different two-dimensional array configurations, the thesis further arranges the antenna elements into a 2 × 2 array with a reduced center-to-center distance of 10.5 mm (approximately 0.95 λ₀ at 27 GHz). The overall dimensions of the 2 × 2 antenna array are 30 mm × 30 mm × 1.575 mm (2.72 λ₀ × 2.72 λ₀ × 0.14 λ₀). The measured 10-dB impedance bandwidth is 25.8% (23.12–29.96 GHz). Although the isolation between adjacent antenna elements exceeds 25 dB, it is still lower than that of the previous two arrays (> 30 dB). Nonetheless, the axial ratio bandwidth within the required operating frequency band is below 3 dB. The maximum gain and efficiency of the 2 × 2 array are slightly higher than those of the 1 × 5 array, at 15.71 dBic and above 74%, respectively. Notably, the 2 × 2 array achieves a beam scanning angle of ±30° at 24.5 GHz, which is between the angles measured for the 1 × 4 and 1 × 5 arrays. However, the beam scanning angles at 28 GHz and 29.5 GHz are slightly reduced to ±28° and ±27°, respectively.
Finally, to further demonstrate that increasing the number of antenna elements in a two-dimensional array can linearly increase the array gain, the thesis expands the 2 × 2 array into a 4 × 4 configuration, maintaining the center-to-center distance at 10.5 mm (approximately 0.95 λ₀ at 27 GHz). The isolation between adjacent antenna elements is similar to that of the 2 × 2 array, exceeding 25 dB, but the overall dimensions increase to 50 mm × 50 mm × 1.575 mm (4.5 λ₀ × 4.5 λ₀ × 0.14 λ₀). The measured results show that the 10-dB impedance bandwidth of the 4 × 4 array is 25.9% (22.9–29.72 GHz), with the axial ratio bandwidth within the required operating frequency band remaining below 3 dB. Compared to the 2 × 2 array, the maximum gain of the 4 × 4 array is 21.83 dBic, approximately 6 dB higher, with an efficiency of over 73%, slightly higher by about 2%. Notably, the beam scanning angles at 24.5 GHz, 28 GHz, and 29.5 GHz are ±38°, ±33°, and ±30°, respectively, all higher than those measured for the 2 × 2 array. Therefore, based on all the experimental results, it can be concluded that the proposed antenna element can be effectively expanded and applied to 5G smartphones and other large communication devices requiring circularly polarized radiation performance.

目錄
摘 要 i
Abstract iv
目錄 viii
圖目錄 xi
表目錄 xvii
縮寫與符號對照表 xviii
第一章 緒論 19
1.2 文獻探討 20
1.3研究動機 36
1.4章節大綱 38
第二章 多層寬頻毫米波陣列天線 39
2.1 天線單元 39
2.1.1天線結構 39
2.1.2設計流程 42
2.1.3模擬與實作結果 47
2.1.4參數模擬與分析 54
A.參數L1之影響分析 55
B.參數L2之影響分析 58
C.參數L3之影響分析 61
2.2天線陣列 64
2.2.1 1 × 4天線陣列模擬結果 64
2.2.2 1 × 5天線陣列模擬結果 76
2.2.3 2 × 2天線陣列模擬結果 88
2.2.4 4 × 4天線陣列模擬結果 100
2.2.5天線效能比較 112
2.2.6天線實作與量測架設 115
第三章 結論 121
參考文獻 124
附錄A 131
累積分布函數 (CDF) 131
附錄B 135
1 × 4天線陣列加入手機載體之模擬結果 135
附錄C 145
2.2.4 1 × 5天線陣列加上手機載體模擬結果 145
附錄D 157
8 × 8天線陣列模擬結果 157
附錄E 168
16 × 16天線陣列模擬結果 168
附錄F 178
陣列設置距離之討論 178
附錄G 182
1 × 4天線陣列及1 × 5天線陣列性能比較 182

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