摘要
超材料是一具人工設計週期性結構的電磁複合材料，近年來被大量應用在天線上，平面共振式天線即為其一應用，平面共振式天線相對於微帶陣列天線而言，是一種兼具平面式與高指向性優點的天線，被提出來取代微帶陣列式天線，以解決饋入網路中傳輸線的損耗所造成天線增益降低的缺點。本研究將超材料應用在高指向性平面共振式天線上，藉由超材料之特性縮小平面共振式天線的體積，以符合現今無線通訊的天線訴求，朝小型、輕量、低功率與高性能的趨勢。本研究藉由改變覆板的反射相位至-45°，基板採用蕈狀結構(mushroom like structure)使之反射相位為135°，進而縮小共振腔高度至λ/8，並且將頻率操作在覆板與基板的截止頻帶產生漏波模態(proper complex leaky-wave modes)，以達到全反射降低能量在基板的損耗，增進主束瓣增益，覆板對於主束瓣而言像是濾波器的特性，可以屏蔽掉某一頻帶的電磁波，也就是前述所言之截止頻帶，當天線的頻率落在此頻帶時，經饋入天線輻射出的電磁波便無法穿透出去，達成頻率選擇。在縮小面積的同時，波易從側面漏出會使得旁波瓣(side lobe level)過大，需加以完美電牆與完美磁牆構成共振腔體。模擬結果使在操作頻率為12 GHz時，面積為2 × 2 λ02的平面共振式天線指向性達15.1 dBi，其aperture efficiency達90 %。

[1] T. I. Christophe Caloz, "Electromagnetic Metamaterials Transmission Line Theory and Microwave Applications," 2005.
[2] H. L. Xu, et al., "Metamaterial superstrate and electromagnetic band-gap substrate for high directive antenna," International Journal of Infrared and Millimeter Waves, vol. 29, pp. 493-498, May 2008.
[3] W. L. Stutzman. and G. A. Thiele, "Antenna Theory and Design," 1998.
[4] M. Thevenot, et al., "Directive photonic-bandgap antennas," Ieee Transactions on Microwave Theory and Techniques, vol. 47, pp. 2115-2122, Nov 1999.
[5] A. A. Kishk, "One-dimensional electromagnetic bandgap for directivity enhancement of waveguide antennas," Microwave and Optical Technology Letters, 2005.
[6] K. P. E. A. R. Weily, B. C. Sanders, and T. S. Bird, , "High-gain 1D EBG resonator antenna,," Microwave and Optical Technology Letters, 2005.
[7] T. M. L. Leger, and B. Jecko, "Enhancement of gain and radiation bandwidth for a planar 1-D EBG antenna," IEEE Microwave and Wireless Components Letters, 2005.
[8] Y. J. Lee, et al., "Directivity enhancement of printed antennas using a class of metamaterial superstrates," Electromagnetics, vol. 26, pp. 203-218, Apr-Jun 2006.
[9] L. Q. Z. Fangming, H. Sailing, H. Jun, and Y. Zhinong, "A high directivity patch antenna using a PBG cover together with a PBG substrate," 2003 6th International Symposium on Antennas, Propagation and EM Theory, 2003.
[10] Z. F. a. L. Qingchun, "High-directivity patch antenna with both perfect magnetic conductor substrate and photonic bandgap cover," Asia-Pacific Conference Proceedings 2005, Microwave Conference Proceedings, 2005.
[11] L. H. A. R. Weily, K. P. Esselle, B. C. Sanders, and T. S. Bird, "A planar resonator antenna based on a woodpile EBG material," Microwave and Optical Technology Letters, 2005.
[12] P. N. F. Frezza, L. Pajewski, and G. Schettini, "FMM and FDTD analysis of a woodpile 3D-EBG superstrate for patch antennas," Microwave and Optical Technology Letters, 2006.
[13] S. Wang, et al., "High-gain subwavelength resonant cavity antennas based on metamaterial ground planes," IEE Proceedings-Microwaves Antennas and Propagation, vol. 153, pp. 1-6, Feb 2006.
[14] Y. H. Ge and K. P. Esselle, "LOW-PROFILE RESONANT CAVITY ANTENNA BASED ON AN IN-PHASE METAMATERIAL SURFACE," Microwave and Optical Technology Letters, vol. 51, pp. 731-739, Mar 2009.
[15] G. Zhao, et al., "DESIGN OF HIGH-GAIN LOW-PROFILE RESONANT CAVITY ANTENNA USING METAMATERIAL SUPERSTRATE," Microwave and Optical Technology Letters, vol. 52, pp. 1855-1858, Aug 2010.
[16] C. Mateo-Segura, et al., "Sub-wavelength profile 2-D leaky-wave antennas with two periodic layers," IEEE Antennas and Propagation Society, Feb. 2011.
[17] 陳怡惠, "Compact High Directivity Planar Resonator
Antenna Based on Frequency Selective Surfaces," 2011.
[18] D. H. W. Erik Lier, Clinton P. Scarborough, Qi Wu & Jeremy A. Bossard, "An octave-bandwidth negligible-loss radiofrequency metamaterial," Nature Materials 10, 252 2011.
[19] B. A. A. O. Roncière, R. Sauleau, K. Mahdjoubi, and H. Legay, "Radiation performance of purely metallic waveguide-fed compact Fabry-Perot antennas for space applications," IEEE Transactions on Antennas and Propagation, 2007.
[20] 江忠信, "Design of planar resonator antennas based on frequency selective surface for directivity enhancement and size reduction," 2007.
[21] T. Zhao, et al., "General Formulas for a 2D Leaky-Wave Antenna," Antennas and Propagation, IEEE Transactions , vol. 53, pp. 3525 - 3533 2005.
[22] G. Lovat, et al., "Fundamental Properties and Optimization
of Broadside Radiation From Uniform
Leaky-Wave Antennas," Antennas and Propagation, IEEE Transactions , vol. 54, pp. 1442 - 1452 May 2006.
[23] D. F. S. A Hosseini, F, Capolino, F, Hosseini, S. A, "A New Formula for the Pattern Bandwidth of Fabry-Pérot Cavity Antennas Covered by Thin Frequency Selective Surfaces," IEEE Transactions on Antennas and Propagation, 2011.
[24] F. Bayatpur, "Metamaterial-Inspired Frequency-Selective Surfaces," 2009.
[25] G. V. TRENTINI, "Partially reeflecting sheet arrays," IRE Transactions on antenna and propagation, 1956.
[26] D. M. Pozar, "Microwave Engineering 3E," 2005.
[27] T. K. Wu, "frequency selective surface and grid array," 1995.
[28] "Ansoft HFSS 輔助說明."