因應通訊科技的快速發展，可重構式技術在天線領域中近年已成為熱門研究課題。本論文內容以頻率可重構式微帶天線以及陣列結構作為主題，設計位於Ku頻段的天線，而我們選擇以液晶這項技術來實現頻率可重構式天線，藉由控制電壓來改變液晶材料的介電係數與介電損耗，來達成頻率可調整的功能。首先設計天線輻射元件，接著將其擴展成四個天線貼片所組成的串聯式中間饋入液晶陣列結構與並聯式液晶陣列結構，最後我們將串聯式中間饋入液晶陣列結構擴充成四個輸入端的4×4大型液晶陣列結構，過程中先透過電磁模擬給予每個饋入端不同的相位差來觀察掃描角度，並分別採用子陣列天線距離0.5波長與0.7波長來觀察指向性變化與波束寬度變化。在模擬軟體實作下，我們發現矩形貼片在微帶線饋入下擁有最高的頻率偏移率與次高的天線增益;而在串聯式中間饋入液晶陣列結構與並聯式液晶陣列結構的比較上，串聯式擁有較高的天線增益與較窄的半功率束寬；特別在0.5波長與0.7波長指向性與波束寬度變化差異上，我們得到0.7波長擁有較高的天線指向性(17.72 ~ 18.02 dB)與較窄的半功率束寬(17.83 ~ 20.62度)，並且有正負42度的波束掃描功能。本論文所使用的天線數量為4×4，而它所能達到在正負42度時的天線增益分別為13.21 dBi與13.08 dBi，與文獻相比本論文所提出的設計不僅在使用天線的數量上較少且在天線增益及掃描角度均有大幅度的領先。

With the rapid development of the communication technology, the reconfigurable technology has been a popular issue for research in recent years. In this thesis, we focus on the frequency reconfigurable and array structures, and design antennas which resonates at Ku-band. We choose to use the liquid crystal technology to realize the function of frequency reconfiguration, which can constantly tune the dielectric coefficient and loss tangent of the material by changing the bias voltage. First, we design the shape of the radiated antenna unit, and then expanded into a four elements array antenna, which its feeding network is composed of series and parallel feed. Finally, we picked up the series feed array antenna to form a four-by-four array antenna with four input ports. According to the full wave simulation results, we could observe the scanning angle by giving each port a different phase difference, besides we separated the array antenna unit by 0.5 and 0.7 wavelength to evaluate the variation of directivity and beamwidth. The simulation results show that rectangular patch under microstrip line feed has the highest performance of frequency tunability and antenna gain, therefore we found that series array antenna has a better antenna gain and a narrower half-power beamwidth between the comparison of series and parallel feed array antenna. Especially when we based on the series array and expand it into a four-by-four antenna array, we found that when the spacing between the antenna unit is 0.7 wavelength, it has better directivity and narrower half power beamwidth, which are 17.72 ~ 18.02 dB and 17.83 ~ 20.62 degrees and can even achieve beam scanning angle range of -36 ~ 36 degrees. The proposed experiment results based on the amounts of 4×4 antenna and beam-steering up to ±36 degrees not only reduce the antenna quantity but also attain gain with 13.21 dBi and 13.08 dBi, respectively, which is much better than the results that we cited.

[1] starlink, https://www.starlink.com/
[2] 電信事業申請衛星固定通信用無線電頻率核配有關事項草案總說明及逐點說明, https://www.ncc.gov.tw/chinese/files/22040/181_47335_220401_1.pdf
[3] Ranjan Mishra, "An Overview of Microstrip Antenna",in HCTL Open International Journal of Technology Innovations and Research (IJTIR), Volume 21, Issue 2, August 2016 e-ISSN: 2321-1814, ISBN (Print): 978-81-932623-1-3
[4] Warren L.Stutzman,"Antenna theory and Design", 3/e, Wiley,2012.
[5] .https://www.analog.com/media/en/analog-dialogue/volume-54/number-2/phased-array-antenna-patterns-part-2-grating-lobes-and-beam-squint.pdf
[6] Jeen-Sheen Row and Chih-Wei Tsai,"Pattern Reconfigurable Antenna Array With Circular Polarization" in IEEE Transactions on Antennas and Propagation Letters, VOL. 64, NO. 4, APRIL 2016, Page(s): 1525 - 1530, DOI: 10.1109/TAP.2016.2522467.
[7] Ming-Chun Tang , Qingli Lin , Mei Li , and Richard W. Ziolkowski,"Polarization-Reconfigurable Yagi-Configured Electrically Small Antenna" in IEEE Transactions on Antennas and Propagation Letters, VOL. 69, NO. 3, MARCH 2021, Page(s): 1757 - 1762, DOI: 10.1109/TAP.2020.3018554.
[8] Mohammod Ali," Reconfigurable Antenna Design and Analysis", Artech House Publishers, 2021.
[9] Anastasis C. Polycarpou, Marios A. Christou, and Nectarios C. Papanicolaou, "Tunable Patch Antenna Printed on a Biased Nematic Liquid Crystal Cell" in IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 62, NO. 10, OCTOBER 2014, DOI: 10.1109/TAP.2014.2344099
[10] J. Kim and J. Oh, "Liquid-Crystal-Embedded Aperture-Coupled Microstrip Antenna for 5G Applications," in IEEE Antennas and Wireless Propagation Letters, vol. 19, no. 11, pp. 1958-1962, Nov. 2020, doi: 10.1109/LAWP.2020.3014715
[11] Dongwei Wang , Ersin Pola, Henning Tesmer,Rolf Jakoby, and Holger Maune,"A Compact and Fast 1 × 4 Continuously Steerable Endfire Phased-Array Antenna Based on Liquid Crystal" in IEEE Transactions on Antennas and Propagation Letters, VOL. 20, NO. 10, OCTOBER 2021, Page(s): 1859 - 1862, DOI: 10.1109/LAWP.2021.3096035.
[12] You Lan, TianLiang Zhang, Di Jiang,"K-band liquid-crystal-based frequency and pattern reconfigurable linear antenna array", in IEEE MTT-S International Wireless Symposium (IWS),May 2018, DOI: 10.1109/IEEE-IWS.2018.8400886.
[13] Xiaoyu Li,Yinglu Wan,Juan Liu, Di Jiang Tianming Bai, Jie Zhuang, and Wen-Qin Wan"Broadband Electronically Scanned Reflectarray Antenna With Liquid Crystals" in IEEE Transactions on Antennas and Propagation Letters, VOL. 20, NO. 3, MARCH 2021, Page(s): 396 - 400, DOI: 10.1109/LAWP.2021.3051797 .
[14] Yajie Mu, Xiaohe Gao, Zhilong Li, Jiaqi Han and Long Li, "Beam Steering for Base Station Antenna Array using Transmission Metasurface Cell" in 2020 IEEE MTT-S International Wireless Symposium (IWS), DOI: 10.1109/IWS49314.2020.9360125
[15] 柯冠州(2021)， "窄頻帶通與液晶複合式頻率選擇技術之研究"，國立台灣科技大學電子工程研究所碩士論文。
[16] Anastasis C. Polycarpou, Marios A. Christou, and Nectarios C. Papanicolaou, "Tunable Patch Antenna Printed on a Biased Nematic Liquid Crystal Cell" in IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 62, NO. 10, OCTOBER 2014, DOI: 10.1109/TAP.2014.2344099
[17] Melad M. Olaimat , "Comparison between Rectangular and Circular Patch Antennas Array", in International Journal of Computational Engineering Research (IJCER), ISSN (e): 2250 – 3005 || Volume, 06 || Issue, 09|| September – 2016 ||
[18] Yahya S. H. Khraisat and Melad M. Olaimat , "Comparison Between Rectangular and Triangular Patch Antennas Array" in 2012 19th International Conference on Telecommunications (ICT), DOI: 10.1109/ICTEL.2012.6221265
[19] Neha Tanzeem Sagar, M. L. Meena and Pankaj Shukla, "DESIGN AND PERFORMANCE ANALYSIS OF UWB CIRCULAR RING ANTENNA
WITH DEFECTED GROUND STRUCTURE" in ICTACT JOURNAL ON COMMUNICATION TECHNOLOGY, DECEMBER 2017, VOLUME: 08, ISSUE: 04
[20] Ghanshyam Mishra, Satish Kumar Sharma, Jia-Chi Samuel Chieh, Randall B. Olsen,"Ku-Band Dual Linear-Polarized 1-D Beam Steering Antenna Using Parabolic-Cylindrical Reflector Fed by a Phased Array Antenna" in IEEE Open Journal of Antennas and Propagation, ( Volume: 1), 03 March 2020, Page(s): 57 – 70, DOI: 10.1109/OJAP.2020.2977876
[21] Yizhe Zhao,Cheng Huang,An-Yong Qing and Xiangang Luo ,"A Frequency and Pattern Reconfigurable Antenna Array Based on Liquid Crystal Technology" in IEEE Photonics Journal, vol. 9, no. 3, pp. 1-7, June 2017, DOI: 10.1109/JPHOT.2017.2700042.
[22] You Lan, TianLiang Zhang, Di Jiang,"K-band liquid-crystal-based frequency and pattern reconfigurable linear antenna array", in IEEE MTT-S International Wireless Symposium (IWS),May 2018, DOI: 10.1109/IEEE-IWS.2018.8400886.
[23] Dongwei Wang , Ersin Pola, Henning Tesmer,Rolf Jakoby, and Holger Maune,"A Compact and Fast 1 × 4 Continuously Steerable Endfire Phased-Array Antenna Based on Liquid Crystal"in IEEE Transactions on Antennas and Propagation Letters, VOL. 20, NO. 10, OCTOBER 2021, Page(s): 1859 - 1862,DOI:10.1109/LAWP.2021.3096035.