圆极化可重构微带天线的研究
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摘要
可重构天线技术是目前天线领域的研究热点。可重构天线可以在同一副天线上实现多副天线的功能,这一技术是为了满足近年来无线通信系统进一步向大容量、多功能、超宽带方向发展的需求而提出的。目前这一研究领域还处于发展阶段,仍然有许多难题需要解决。
本文对可重构天线其中的一种形式――极化可重构天线做了初步的探索。在简要介绍了微带天线和极化的相关知识后,本文分析了无线通信系统尤其是MIMO系统采用圆极化天线的优势,随后,在归纳总结了近年来极化可重构天线研究成果的基础上,采用圆环缝隙结构设计极化可重构天线。
首先通过理论分析和软件数值仿真,分析了圆环缝隙天线参数变化对其性能的影响,并通过仿真验证了文中提出的两种扩展天线带宽的方法,两种方法可将天线带宽提高将近4倍。然后根据圆极化形成的基本原理,改变圆环缝隙结构天线馈电网络,分别设计了右旋圆极化和左旋圆极化的天线。
随后,基于右旋和左旋圆极化天线结构上的对称性,在天线上引入MEMS开关,设计了左右旋圆极化可重构天线。借助仿真软件,分析影响该天线性能的因素并在结构上加以改进和重新设计,得到性能上满足要求的天线结构。最后,将扩展带宽的方法应用到该天线上面,通过仿真和实测,证明该方法在不明显增加天线体积情况下,有效提高了天线带宽。
The research on reconfigurable antenna technology is one of the hot spot in antenna field nowadays. The reconfigurable antenna can fulfill functions of multi-antenna on only on antenna, in order to increase the capabilities and functions of wireless integrated information systems and widen their bandwidths, overcome the drawbacks, the concept of reconfigurable antenna is presented. At present, this work is still at developing stage, and much unknown domains need to be overcome.
In this paper, one kind of reconfigurable antenna--polarization reconfigurable antenna is analyzed preliminary, after brief introduction of microstrip antenna and polarization, advantages of adopting circular polarization antenna in wireless communication systems especially MIMO system is analyzed. Based on the summary of research results on polarization reconfigurable antenna of the world in recent years, ring slot structure is adopted to design polarization reconfigurable antenna.
Through the theoretically analyze and numerical emulation, effect of parameters modification on ring slot structure antenna is analyzed. Two kinds of method which can widen antenna's bandwidths for 4 times is presented and validated through emulation. Thereafter, based on the theory of circular polarization, through modifying feed network of antenna, clockwise and counter-clockwise circular polarization antenna are designed respectively.
Based on the symmetrical of clockwise and counter-clockwise circular polarization antenna structure, MEMS switch are used on antenna, clockwise and counter-clockwise circular polarization reconfigurable antenna is designed. Resorted to emulator software, effects of parameters on antenna performance analyze and structure of antenna modified, then the structure satisfied request is obtained. At last, the method of widen antenna's bandwidth is adopted, through emulation and measured, this method is proved to be availability.
本文对可重构天线其中的一种形式――极化可重构天线做了初步的探索。在简要介绍了微带天线和极化的相关知识后,本文分析了无线通信系统尤其是MIMO系统采用圆极化天线的优势,随后,在归纳总结了近年来极化可重构天线研究成果的基础上,采用圆环缝隙结构设计极化可重构天线。
首先通过理论分析和软件数值仿真,分析了圆环缝隙天线参数变化对其性能的影响,并通过仿真验证了文中提出的两种扩展天线带宽的方法,两种方法可将天线带宽提高将近4倍。然后根据圆极化形成的基本原理,改变圆环缝隙结构天线馈电网络,分别设计了右旋圆极化和左旋圆极化的天线。
随后,基于右旋和左旋圆极化天线结构上的对称性,在天线上引入MEMS开关,设计了左右旋圆极化可重构天线。借助仿真软件,分析影响该天线性能的因素并在结构上加以改进和重新设计,得到性能上满足要求的天线结构。最后,将扩展带宽的方法应用到该天线上面,通过仿真和实测,证明该方法在不明显增加天线体积情况下,有效提高了天线带宽。
The research on reconfigurable antenna technology is one of the hot spot in antenna field nowadays. The reconfigurable antenna can fulfill functions of multi-antenna on only on antenna, in order to increase the capabilities and functions of wireless integrated information systems and widen their bandwidths, overcome the drawbacks, the concept of reconfigurable antenna is presented. At present, this work is still at developing stage, and much unknown domains need to be overcome.
In this paper, one kind of reconfigurable antenna--polarization reconfigurable antenna is analyzed preliminary, after brief introduction of microstrip antenna and polarization, advantages of adopting circular polarization antenna in wireless communication systems especially MIMO system is analyzed. Based on the summary of research results on polarization reconfigurable antenna of the world in recent years, ring slot structure is adopted to design polarization reconfigurable antenna.
Through the theoretically analyze and numerical emulation, effect of parameters modification on ring slot structure antenna is analyzed. Two kinds of method which can widen antenna's bandwidths for 4 times is presented and validated through emulation. Thereafter, based on the theory of circular polarization, through modifying feed network of antenna, clockwise and counter-clockwise circular polarization antenna are designed respectively.
Based on the symmetrical of clockwise and counter-clockwise circular polarization antenna structure, MEMS switch are used on antenna, clockwise and counter-clockwise circular polarization reconfigurable antenna is designed. Resorted to emulator software, effects of parameters on antenna performance analyze and structure of antenna modified, then the structure satisfied request is obtained. At last, the method of widen antenna's bandwidth is adopted, through emulation and measured, this method is proved to be availability.
引文
[1] C. A. Balanis, Anttern theory: analysis and design, Second edition, New York: Wiley, 1997, 2-3
[2] John D, Kraus and Ronald J, Marheflca著,章文勋译,天线(第三版)(上册),北京:电子工业出版社,2004,1-2
[3]林昌禄,近代天线设计,北京:人民邮电出版社,1990,3-5
[4] K. Chang, RF and microwave wireless systems, New York: Wiley, 2000
[5] E. Lee, P. S. Hall and P. Gardner, Compact wideband planar monopole antenna, IEE Electron.Lett., 1999, 35, 2157-2158
[6] D. Schaubert, F. Farrar, S. Hayes, etal, Frequency-agile, polarization diverse microstrip antennas and frequency scanned arrays, US Patent #4,367,474,1983, Jan(4)
[7] J. K. Smith, Reconfigurable program(RECAP), DARPA(美国国防高级研究计划署),1999
[8] J. H. Winters, On the capacity of radio communication systems with diversity in a Rayleigh fading environment, IEEE J. Select Areas Communication, 1987, vol. SAC-5(6) ,871-878
[9] G. J. Foschini and M. J. Gans, On limits of wireless communications in a fading environment when using multiple antennas, Wireless Personal Commun, 1998(3), 311-355
[10] T. L. Marzetta and B. M. Hochwald, Capacity of a mobile multiple-antenna communication link in Rayleigh flat fading, IEEE Trans. Inform. Theory, 1999, 45(1), 139-157
[11] G.. G.. Raleigh and J. M. Cioffi, Spatio-temporal coding for wireless communication, IEEE Trans. Commun., 1998, 46(3), 357-366
[12] Marc Mowler, Bjom Lindmark, Joachim Oberhammer etal, A 2-bit Reconfigurable Meander Slot Antenna with RF-MEMS Switches, Antennas and Propagation Society International Symposium 2005, 2005,3-8(7) 396-399
[13] Sunan Liu, Ming-Jer Lee, Chang won Jung etal, A Frequency-Reconfigurable Circularly Polarized Patch Antenna by Integrating MEMS Switches,Antennas and Propagation Society International Symposium 2005,2005, 3-8(7), 413-416
[14] James T.Aberle, Sung-Hoon Oh, David T, Auckland et al.Reconfigurable Antenna for Portable Wireless Devices.IEEE Antennas and Propagation Magazine, 2003, 45(6), 148-154.
[15] Emre Erdil,Kagan Topalli,Mehmet Unlu et al.Frequency Tunable Microstrip Patch Antenna Using RF MEMS Technology.IEEE Transactions on Antennas and Propagation, 2007, 55(4), 1193-1196.
[16] Dimitrios E.Anagnostou,Guizhen Zheng,Michael T.Chryssomallis et al . Design , Fabrication , and Measurements of an RF-MEMS-Based Self-Similar Reconfigurable Antenna.IEEE Transactions on Antennas and Propagation,2006, 54(2), 422-432.
[17] Xue-Song Yang,Bing-Zhong Wang,Yong Zhang.Reconfigurable Hilbert Curve Patch Antenna.IEEE International Workshop on Antenna Technology:Small Antennas and Novel Metamaterials,2005, 2005, 7-9(3), 521-524.
[18] Yong Zhang,Bing-Zhong Wang,Weixia Wu.A Fractal Hilbert Microstrip Antenna with Reconfigurable Radiation Patterns, 2005, 3-8(7),254-257
[19] Greg H.Huff,Jennifer T.Bernhard.Integration of Packaged RF MEMS Switches with Radiation Pattern Reconfigurable Square Spiral Microstrip Antennas, IEEE Transactions on Antennas and Propagation, 2006, 54(2), 464-469.
[20] Laurent Petit,Laurent Dussopt,Jean-Marc Laheurte.MEMS-Switched Parasitic-Antenna Array for Radiation Pattern Diversity[J].IEEE Transactions on Antennas and Propagation, 2006, 54(9), 2624-2631.
[21] Chang won Jung,Ming-jer Lee,G.P.Li et al.Reconfigurable Scan-Beam Single-Arm Spiral Antenna Integrated with RF-MEMS Switches[J].IEEE Transactions on Antennas and Propagation,2006, 54(2), 455-463.
[22]钟顺时,微带天线理论与应用,西安:西安电子科技大学出版社,1991,2-3
[23] I.J.鲍尔,P.布哈蒂亚,微带天线,北京:电子工业出版社,1984,11-12
[24] LAL CHAND GODARA,无线通信天线手册,北京:国防工业出版社,2004,152-154
[25]张云,阮成礼,彭麟,宽带小型微带天线研究综述,2007年全国微波毫米波会议论文集,361-364
[26] Special issue on software radio.IEEE Personal Commun. 1999, 24(6)
[27]阮成礼,超宽带天线理论与技术,哈尔滨:哈尔滨工业大学出版社,2006
[28] Ishimaru A. Wave Propagation and Scattering in Random Media, Academic Press, New York, 1978
[29] Vaughan R G Polarization diversity in mobile communications. IEEE Trans. Vehi. Tech., 1990, 39(8), 177-186
[30] Shafi M, Zhang M, et al. Polarized MIMO Channels in 3D: Models, Measurements and Mutual Information. IEEE J. Selected Areas Comm, 2006, 24(3), 514-527
[31]高向军,王光明,朱莉,宽带圆极化微带天线的设计,天线与伺服技术, 2007,33(1), 34-36
[32]薛睿峰,钟顺时,微带天线圆极化技术概述与进展,电波科学学报, 2002,17(4),331-336
[33] A.Fathy, etal, Silicon Based reconfigurable antennas, IEEE AP-S, 2000,325-326
[34] K.C.Gupta,etal, Design of frequency-reconfigurable rectangular slot ring antenna, IEEE,2000, AP-S,326-326
[35] Andre Calmon, Guilherme Pacheco, Marco Terada, A Novel Reconfigurable UWB Log-Periodic Antenna, 2006, 9-14(7), 213-216
[36] Dimitrios E, Anagnostou, Guizhen Zheng, Michael T, etal, Design, Fabrication and Measurements of an RF-MEMS-Based Self-Similar Reconfigurable Antenna, IEEE Transactions on Antennas and Propagation, 2006, 54(2), 422-432
[37] J.H.Schaffner, Reconfigurable aperture antenna using RF MEMS switches for multi-octave tenability and beam steering, IEEE, 2000, AP-S, 321-324
[38] B.Elamaran, A beam-steerer using reconfigurable PBG ground plane, IEEE, 2000, AP-S, 835-838.
[39] P.J.B.Clarricoats, H.Zhou, Design and performance of a reconfigurable mesh reflector antenna, Part 1:Antenna design.IEE Proceedings H.Microwaves,Antennas and Propagation, 1991,138(6), 485-49.
[40] Xue-Song Yang, Bing-Zhong Wang, Weixia Wu, Pattern Reconfigurable Patch Antenna with Two Orthogonal Quasi-Yagi Arrays, 2005,3-9(7), 617-620
[41] K.J.Vinoy, Hilbert curve fractal antennas with reconfigurable characteristics, IEEE MTT-S, 2001,381-384
[42] Wang Kin-Lu, Compact and Broaband Microstrip Antennas, A Wiley-Interscience Publication ,2002
[43]陈燕仙,MEMS开关可重构天线的研究与设计,华东师范大学,2005
[44] Fan Yang, A Reconfigurable Patch Antenna Using Switchable Slots for Circular Polarization Diversity, IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, 2002,12(3), 55-56
[45] Fan Yang , Yahya Rahmat-Samii, Patch Antennas with Switchable Slots (PASS) in Wireless Communications: Concepts, Designs, and Applications, IEEEAntennas and Propagation Magazine, 2005,47(2),78-79
[46] Nanbo Jin, Fan Yang, and Yahya Rahmat-Samii, A Novel Patch Antenna With Switchable Slot (PASS):Dual-Frequency Operation With Reversed Circular Polarizations,IEEE TRANSACTIONS ON ANTENNAS ANDPROPAGATION, 2006, 54(3), 35-36
[47] BelhaehatMessaouda,电可重构天线的研究,华东师范大学,2004
[48] Matthias K. Fries, A Reconfigurable Slot Antenna With Switchable Polarization , IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, 2003, 13(11), 45-47
[49] Y. J. Sung, T. U. Jang, and Y.-S. Kim, A Reconfigurable Microstrip Antenna for Switchable Polarization, IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, 2004, 14(11), 41-46
[50]伍裕江,聂在平,乐铁军,基于极化可重构天线的天线选择方案,电子学报,2007,35(12),23-26
[51] Shing-Lung Steven Yang and Kwai-Man Luk, A Wideband L-Probes Fed Circularly-Polarized Reconfigurable Microstrip Patch Antenna, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 2008,56(2)
[52] Boyon Kim, Bo Pan, Symeon Nikolaou,etc, A Novel Single-Feed Circular Microstrip Antenna With Reconfigurable Polarization Capability, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 2008, 56(3)
[53] Symeon Nikolaou,Ramanan Bairavasubramanian,Cesar Lugo et al.Pattern and Frequency Reconfigurable Annular Slot Antenna Using PIN Diodes[J].IEEE Transactions on Antennas and Propagation,2006, 54(2), 439-448
[54] Chang won Jung, Ming-jer Lee, G. P. Li, etc, Reconfigurable Scan-Beam Single-Arm SpiralAntenna Integrated With RF-MEMS Switches, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 2006,54(2)
[55] Nader Behdad, Kamal Sarabandi, A Wideband Bi-Semicircular Slot Antenna, Antennas and Propagation Society International Symposium, 2004. IEEE, 2004, 2(6) ,1903-1906
[2] John D, Kraus and Ronald J, Marheflca著,章文勋译,天线(第三版)(上册),北京:电子工业出版社,2004,1-2
[3]林昌禄,近代天线设计,北京:人民邮电出版社,1990,3-5
[4] K. Chang, RF and microwave wireless systems, New York: Wiley, 2000
[5] E. Lee, P. S. Hall and P. Gardner, Compact wideband planar monopole antenna, IEE Electron.Lett., 1999, 35, 2157-2158
[6] D. Schaubert, F. Farrar, S. Hayes, etal, Frequency-agile, polarization diverse microstrip antennas and frequency scanned arrays, US Patent #4,367,474,1983, Jan(4)
[7] J. K. Smith, Reconfigurable program(RECAP), DARPA(美国国防高级研究计划署),1999
[8] J. H. Winters, On the capacity of radio communication systems with diversity in a Rayleigh fading environment, IEEE J. Select Areas Communication, 1987, vol. SAC-5(6) ,871-878
[9] G. J. Foschini and M. J. Gans, On limits of wireless communications in a fading environment when using multiple antennas, Wireless Personal Commun, 1998(3), 311-355
[10] T. L. Marzetta and B. M. Hochwald, Capacity of a mobile multiple-antenna communication link in Rayleigh flat fading, IEEE Trans. Inform. Theory, 1999, 45(1), 139-157
[11] G.. G.. Raleigh and J. M. Cioffi, Spatio-temporal coding for wireless communication, IEEE Trans. Commun., 1998, 46(3), 357-366
[12] Marc Mowler, Bjom Lindmark, Joachim Oberhammer etal, A 2-bit Reconfigurable Meander Slot Antenna with RF-MEMS Switches, Antennas and Propagation Society International Symposium 2005, 2005,3-8(7) 396-399
[13] Sunan Liu, Ming-Jer Lee, Chang won Jung etal, A Frequency-Reconfigurable Circularly Polarized Patch Antenna by Integrating MEMS Switches,Antennas and Propagation Society International Symposium 2005,2005, 3-8(7), 413-416
[14] James T.Aberle, Sung-Hoon Oh, David T, Auckland et al.Reconfigurable Antenna for Portable Wireless Devices.IEEE Antennas and Propagation Magazine, 2003, 45(6), 148-154.
[15] Emre Erdil,Kagan Topalli,Mehmet Unlu et al.Frequency Tunable Microstrip Patch Antenna Using RF MEMS Technology.IEEE Transactions on Antennas and Propagation, 2007, 55(4), 1193-1196.
[16] Dimitrios E.Anagnostou,Guizhen Zheng,Michael T.Chryssomallis et al . Design , Fabrication , and Measurements of an RF-MEMS-Based Self-Similar Reconfigurable Antenna.IEEE Transactions on Antennas and Propagation,2006, 54(2), 422-432.
[17] Xue-Song Yang,Bing-Zhong Wang,Yong Zhang.Reconfigurable Hilbert Curve Patch Antenna.IEEE International Workshop on Antenna Technology:Small Antennas and Novel Metamaterials,2005, 2005, 7-9(3), 521-524.
[18] Yong Zhang,Bing-Zhong Wang,Weixia Wu.A Fractal Hilbert Microstrip Antenna with Reconfigurable Radiation Patterns, 2005, 3-8(7),254-257
[19] Greg H.Huff,Jennifer T.Bernhard.Integration of Packaged RF MEMS Switches with Radiation Pattern Reconfigurable Square Spiral Microstrip Antennas, IEEE Transactions on Antennas and Propagation, 2006, 54(2), 464-469.
[20] Laurent Petit,Laurent Dussopt,Jean-Marc Laheurte.MEMS-Switched Parasitic-Antenna Array for Radiation Pattern Diversity[J].IEEE Transactions on Antennas and Propagation, 2006, 54(9), 2624-2631.
[21] Chang won Jung,Ming-jer Lee,G.P.Li et al.Reconfigurable Scan-Beam Single-Arm Spiral Antenna Integrated with RF-MEMS Switches[J].IEEE Transactions on Antennas and Propagation,2006, 54(2), 455-463.
[22]钟顺时,微带天线理论与应用,西安:西安电子科技大学出版社,1991,2-3
[23] I.J.鲍尔,P.布哈蒂亚,微带天线,北京:电子工业出版社,1984,11-12
[24] LAL CHAND GODARA,无线通信天线手册,北京:国防工业出版社,2004,152-154
[25]张云,阮成礼,彭麟,宽带小型微带天线研究综述,2007年全国微波毫米波会议论文集,361-364
[26] Special issue on software radio.IEEE Personal Commun. 1999, 24(6)
[27]阮成礼,超宽带天线理论与技术,哈尔滨:哈尔滨工业大学出版社,2006
[28] Ishimaru A. Wave Propagation and Scattering in Random Media, Academic Press, New York, 1978
[29] Vaughan R G Polarization diversity in mobile communications. IEEE Trans. Vehi. Tech., 1990, 39(8), 177-186
[30] Shafi M, Zhang M, et al. Polarized MIMO Channels in 3D: Models, Measurements and Mutual Information. IEEE J. Selected Areas Comm, 2006, 24(3), 514-527
[31]高向军,王光明,朱莉,宽带圆极化微带天线的设计,天线与伺服技术, 2007,33(1), 34-36
[32]薛睿峰,钟顺时,微带天线圆极化技术概述与进展,电波科学学报, 2002,17(4),331-336
[33] A.Fathy, etal, Silicon Based reconfigurable antennas, IEEE AP-S, 2000,325-326
[34] K.C.Gupta,etal, Design of frequency-reconfigurable rectangular slot ring antenna, IEEE,2000, AP-S,326-326
[35] Andre Calmon, Guilherme Pacheco, Marco Terada, A Novel Reconfigurable UWB Log-Periodic Antenna, 2006, 9-14(7), 213-216
[36] Dimitrios E, Anagnostou, Guizhen Zheng, Michael T, etal, Design, Fabrication and Measurements of an RF-MEMS-Based Self-Similar Reconfigurable Antenna, IEEE Transactions on Antennas and Propagation, 2006, 54(2), 422-432
[37] J.H.Schaffner, Reconfigurable aperture antenna using RF MEMS switches for multi-octave tenability and beam steering, IEEE, 2000, AP-S, 321-324
[38] B.Elamaran, A beam-steerer using reconfigurable PBG ground plane, IEEE, 2000, AP-S, 835-838.
[39] P.J.B.Clarricoats, H.Zhou, Design and performance of a reconfigurable mesh reflector antenna, Part 1:Antenna design.IEE Proceedings H.Microwaves,Antennas and Propagation, 1991,138(6), 485-49.
[40] Xue-Song Yang, Bing-Zhong Wang, Weixia Wu, Pattern Reconfigurable Patch Antenna with Two Orthogonal Quasi-Yagi Arrays, 2005,3-9(7), 617-620
[41] K.J.Vinoy, Hilbert curve fractal antennas with reconfigurable characteristics, IEEE MTT-S, 2001,381-384
[42] Wang Kin-Lu, Compact and Broaband Microstrip Antennas, A Wiley-Interscience Publication ,2002
[43]陈燕仙,MEMS开关可重构天线的研究与设计,华东师范大学,2005
[44] Fan Yang, A Reconfigurable Patch Antenna Using Switchable Slots for Circular Polarization Diversity, IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, 2002,12(3), 55-56
[45] Fan Yang , Yahya Rahmat-Samii, Patch Antennas with Switchable Slots (PASS) in Wireless Communications: Concepts, Designs, and Applications, IEEEAntennas and Propagation Magazine, 2005,47(2),78-79
[46] Nanbo Jin, Fan Yang, and Yahya Rahmat-Samii, A Novel Patch Antenna With Switchable Slot (PASS):Dual-Frequency Operation With Reversed Circular Polarizations,IEEE TRANSACTIONS ON ANTENNAS ANDPROPAGATION, 2006, 54(3), 35-36
[47] BelhaehatMessaouda,电可重构天线的研究,华东师范大学,2004
[48] Matthias K. Fries, A Reconfigurable Slot Antenna With Switchable Polarization , IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, 2003, 13(11), 45-47
[49] Y. J. Sung, T. U. Jang, and Y.-S. Kim, A Reconfigurable Microstrip Antenna for Switchable Polarization, IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, 2004, 14(11), 41-46
[50]伍裕江,聂在平,乐铁军,基于极化可重构天线的天线选择方案,电子学报,2007,35(12),23-26
[51] Shing-Lung Steven Yang and Kwai-Man Luk, A Wideband L-Probes Fed Circularly-Polarized Reconfigurable Microstrip Patch Antenna, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 2008,56(2)
[52] Boyon Kim, Bo Pan, Symeon Nikolaou,etc, A Novel Single-Feed Circular Microstrip Antenna With Reconfigurable Polarization Capability, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 2008, 56(3)
[53] Symeon Nikolaou,Ramanan Bairavasubramanian,Cesar Lugo et al.Pattern and Frequency Reconfigurable Annular Slot Antenna Using PIN Diodes[J].IEEE Transactions on Antennas and Propagation,2006, 54(2), 439-448
[54] Chang won Jung, Ming-jer Lee, G. P. Li, etc, Reconfigurable Scan-Beam Single-Arm SpiralAntenna Integrated With RF-MEMS Switches, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 2006,54(2)
[55] Nader Behdad, Kamal Sarabandi, A Wideband Bi-Semicircular Slot Antenna, Antennas and Propagation Society International Symposium, 2004. IEEE, 2004, 2(6) ,1903-1906