超宽带半圆片全向天线的设计
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摘要
随着超宽带技术的飞速发展,超宽带天线的研究受到人们越来越多的关注。在点对多点的超宽带通信系统中,水平方向上信号的全向覆盖被要求,进而要求辐射或接收天线拥有超宽频带内稳定的水平方向全向辐射方向图。常用的超宽带全向天线包括拥有渐变结构辐射器的单极子天线等。
本文以超宽带圆片单极子天线为基础,在保持超宽带特性的同时,努力改善其H面方向图的全向辐射特性。通过理论分析、计算机仿真和实物加工测试等手段,对天线的设计进行了系统的分析。
通过对圆片单极子天线的仿真分析可知,该天线具有超宽的阻抗带宽,随着频率的升高H面辐射方向图由全向变为双向,对圆片的切削和翻折是两种有效的小型化手段。水平方向上几何结构的对称性是全向辐射的必要条件,因而提出了多圆片等角交叉的天线结构,并分析了圆片数目对各方向增益的最大差异的影响。仿真数据表明,随着圆片数目的增多,天线H面方向图的全向性变优,当片数不小于4时即可满足全向辐射条件；但随着圆片数目的增多,输入阻抗的实部逐渐变小、虚部逐渐变大,天线无法在超宽频带内实现阻抗匹配。
通过仿真分析提出了一种双圆片嵌套结构,用以消除多圆片交叉结构对天线输入阻抗的影响,效果良好。用一个空心圆锥体代替单极子天线中的大尺寸地板,以实现天线水平方向上的尺寸小型化。根据以上分析,提出了超宽带半圆片交叉结构全向天线模型,并对其进行频域和时域的仿真分析,结果表明该天线具有极好的超宽带特性和全向辐射特性,时域特性亦能满足超宽带要求。以该天线模型为基础,加工了三个不同尺寸的天线实物并进行测量,测量结果与仿真结果基本一致,且证明了该天线极佳的超宽带潜能,可实现接近100:1的阻抗带宽。
针对改进的超宽带半圆片天线,提出了若干种频带扩展和天线小型化的方法,具体包括多圆片嵌套结构、拉杆结构、电阻加载和顶部加金属圆片,仿真结果表明均为有效的改善天线阻抗特性的方法,有较高的实用价值。本文设计的天线在超宽带通信、电磁侦察等领域会有广泛的应用。
With the development of ultra-wideband technology, research on UWB antennas gains more and more attention. In point-to-multipoint UWB communication systems, omni-directional coverage of horizontal signals is required, so the horizontal radiation pattern of the radiating or receiving antenna should be stable and omni-directional in the ultrawide frequency range. Common UWB omni-directional antennas are monopole antennas which have radiators of gradually variational structure.
Design in this dissertation is based on UWB circular disk monopole antenna. Omni-directional radiation characteristic of H-plane radiation patterns should be improved as well as the maintenance of ultrawide bandwidth. Combination of theoretical analysis, computer simulation and prototype manufacture helps realize the systemic analysis of antenna design.
Simulation of circular disk monopole antenna shows it has ultrawide impedance bandwidth, H-plane radiation patterns change from omni-direction to bi-direction with the increase of frequency, and cutting and turnover are two efficient miniaturization methods. The geometrical symmetric structure is the essential condition of omni-directional radiation, so antenna with multi disks crossed is proposed, and the effect of disk number on the maximal difference between gain in different direction is analyzed. The simulated results show that with the increase of disk number, the omni-directional characteristic of H-plane radiation pattern is improved, and the condition of omni-directional radiation can be met when the disk number is no less than 4. However, with the increase of disk number, the real part of input impedance gets smaller and the imaginary part gets larger which means the antenna can't maintain impedance matching in the ultrawide bandwidth.
An antenna with combination of two circular disks is proposed to eliminate the effect of multi-disk structure on the input impedance with good results shown. A hollow cone is used to replace the large ground plane in the monopole antenna in order to realize miniaturization in the horizontal plane. According to the analysis above, the UWB omni-directional antenna with crossed disks is presented and simulated in the frequency domain and the time domain. The results show that the antenna has excellent UWB characteristic and omni-directional radiation characteristic, and the time-domain characteristic also meets the UWB requirement. Based on this structure, three antenna prototypes of different dimensions are manufactured and measured with results consistent with simulated ones. Excellent UWB potential of this antenna is also certified which can realize a bandwith of approximately 100:1.
According to the improved UWB semicircular disk antenna, methods of broadening the frequency range and miniaturization are proposed, including nested structure of multi disks, antenna with pulling poles, resistence loading and addition of top metal circular disk. The simulated results show that these methods all can improve the impedance characteristic of the antenna to a certain extent, showing great practical value. The antennas presented in this paper can be used widely in UWB communication, electromagnetic investigation and so on.
本文以超宽带圆片单极子天线为基础,在保持超宽带特性的同时,努力改善其H面方向图的全向辐射特性。通过理论分析、计算机仿真和实物加工测试等手段,对天线的设计进行了系统的分析。
通过对圆片单极子天线的仿真分析可知,该天线具有超宽的阻抗带宽,随着频率的升高H面辐射方向图由全向变为双向,对圆片的切削和翻折是两种有效的小型化手段。水平方向上几何结构的对称性是全向辐射的必要条件,因而提出了多圆片等角交叉的天线结构,并分析了圆片数目对各方向增益的最大差异的影响。仿真数据表明,随着圆片数目的增多,天线H面方向图的全向性变优,当片数不小于4时即可满足全向辐射条件；但随着圆片数目的增多,输入阻抗的实部逐渐变小、虚部逐渐变大,天线无法在超宽频带内实现阻抗匹配。
通过仿真分析提出了一种双圆片嵌套结构,用以消除多圆片交叉结构对天线输入阻抗的影响,效果良好。用一个空心圆锥体代替单极子天线中的大尺寸地板,以实现天线水平方向上的尺寸小型化。根据以上分析,提出了超宽带半圆片交叉结构全向天线模型,并对其进行频域和时域的仿真分析,结果表明该天线具有极好的超宽带特性和全向辐射特性,时域特性亦能满足超宽带要求。以该天线模型为基础,加工了三个不同尺寸的天线实物并进行测量,测量结果与仿真结果基本一致,且证明了该天线极佳的超宽带潜能,可实现接近100:1的阻抗带宽。
针对改进的超宽带半圆片天线,提出了若干种频带扩展和天线小型化的方法,具体包括多圆片嵌套结构、拉杆结构、电阻加载和顶部加金属圆片,仿真结果表明均为有效的改善天线阻抗特性的方法,有较高的实用价值。本文设计的天线在超宽带通信、电磁侦察等领域会有广泛的应用。
With the development of ultra-wideband technology, research on UWB antennas gains more and more attention. In point-to-multipoint UWB communication systems, omni-directional coverage of horizontal signals is required, so the horizontal radiation pattern of the radiating or receiving antenna should be stable and omni-directional in the ultrawide frequency range. Common UWB omni-directional antennas are monopole antennas which have radiators of gradually variational structure.
Design in this dissertation is based on UWB circular disk monopole antenna. Omni-directional radiation characteristic of H-plane radiation patterns should be improved as well as the maintenance of ultrawide bandwidth. Combination of theoretical analysis, computer simulation and prototype manufacture helps realize the systemic analysis of antenna design.
Simulation of circular disk monopole antenna shows it has ultrawide impedance bandwidth, H-plane radiation patterns change from omni-direction to bi-direction with the increase of frequency, and cutting and turnover are two efficient miniaturization methods. The geometrical symmetric structure is the essential condition of omni-directional radiation, so antenna with multi disks crossed is proposed, and the effect of disk number on the maximal difference between gain in different direction is analyzed. The simulated results show that with the increase of disk number, the omni-directional characteristic of H-plane radiation pattern is improved, and the condition of omni-directional radiation can be met when the disk number is no less than 4. However, with the increase of disk number, the real part of input impedance gets smaller and the imaginary part gets larger which means the antenna can't maintain impedance matching in the ultrawide bandwidth.
An antenna with combination of two circular disks is proposed to eliminate the effect of multi-disk structure on the input impedance with good results shown. A hollow cone is used to replace the large ground plane in the monopole antenna in order to realize miniaturization in the horizontal plane. According to the analysis above, the UWB omni-directional antenna with crossed disks is presented and simulated in the frequency domain and the time domain. The results show that the antenna has excellent UWB characteristic and omni-directional radiation characteristic, and the time-domain characteristic also meets the UWB requirement. Based on this structure, three antenna prototypes of different dimensions are manufactured and measured with results consistent with simulated ones. Excellent UWB potential of this antenna is also certified which can realize a bandwith of approximately 100:1.
According to the improved UWB semicircular disk antenna, methods of broadening the frequency range and miniaturization are proposed, including nested structure of multi disks, antenna with pulling poles, resistence loading and addition of top metal circular disk. The simulated results show that these methods all can improve the impedance characteristic of the antenna to a certain extent, showing great practical value. The antennas presented in this paper can be used widely in UWB communication, electromagnetic investigation and so on.
引文
[1]Yarovoy A G, Ligthart L P. UWB Radar:Recent Technological Advances and Applications[C]. Radar Conference, Boston, Massachusetts, U.S.,2007: 43-48.
[2]McEwan T. Body Monitoring and Imaging Apparatus and Method[P].1994, Aug.9:5,573,012.
[3]Craddock I J, Klemm M, Leendertz J, et al. Development and Application of a UWB Radar System for Breast Imaging[C]. Antennas and Propagation Conference, Loughborough, UK,2008:24-27.
[4]Zhuge X, Savelyev T G, Yarovoy A G. Assessment of Electromagnetic Requirements for UWB Through-wall Radar[C]. International Conference on Electromagnetics in Advanced Applications, Torino, Italy,2007:923-926.
[5]Ossberger G, Buchegger T, Schimback E, et al. Non-invasive Respiratory Movement Detection and Monitoring of Hidden Humans Using Ultra Wideband Pulse Radar[C]. International Workshop on Ultra Wideband Systems Joint with Conference on Ultrawideband Systems and Technologies, Kyoto, Japan,2004:395-399.
[6]黎海涛.超宽带无线通信的进展[J].信息网络,2003,(8)：23-25.
[7]Chong C C, Watanabe F, Inamura H. Potential of UWB Technology for the Next Generation Wireless Communications[C]. IEEE Ninth International Symposium on Spread Spectrum Techniques and Applications, Manaus, Brazil, 2006:422-429.
[8]Martigne P. UWB for Low Data Rate Applications:Technology Overview and Regulatory Aspects[C]. IEEE International Symposium on Circuits and Systems, Island of Kos, Greece,2006:2428.
[9]Molisch A F, Balakrishnan K, Cassioli D, et al. IEEE 802.15.4a Channel Model-Final Report[R]. IEEE Document 15-04-662-004-004a.
[10]Mahfouz M R, Zhang C, Merkl B C, et al. Investigation of High-accuracy Indoor 3-D Positioning Using UWB Technology [J]. IEEE Transactions on Microwave Theory and Techniques,2008,56(6):1316-1330.
[11]Multispectral Solutions Inc.. Sapphire DART (RTLS) Product Data Sheet[EB/OL]. (2007). http://www.multispectral.com/pdf/Sapphire_DART. pdf.
[12]Ubisense. Hardware Datasheet(EB/OL). (2006). http://www.ubisense.net /SITE/UPLOAD/Document/TechDocs/Ubisense hardware datasheet May 20 06.pdf.
[13]Meier C, Terzis A, Lindenmeier S. A Robust 3-D High-precision Radio Location System[C]. IEEE/MTT-S International Microwave Symposium, Honolulu, Hawaii, U.S.,2007:397-400.
[14]Pozar D M. Closed-form Approximations for Link Loss in a UWB Radio System Using Small Antennas[J]. IEEE Transactions on Antennas and Propagation,2003,51(9):2346-2352.
[15]Hansen R C. Microwave scanning antennas:Vol Ⅱ. Array Theory and Practice. U.S.:Academic Press,1964.
[16]Mayes P E. Frequency-independent Antennas and Broad-band Derivative thereof[C]. Proceedings of the IEEE,1992,80(1):103-112.
[17]Schwering F K. Millimeter Wave Antennas[C]. Proceedings of the IEEE,1992, 80(1):92-102.
[18]Kummer W H. Basic Array Theory[C]. Proceedings of the IEEE,1992,80(1): 127-140.
[19]Mailloux R J. Antenna Array Architecture[C]. Proceedings of the IEEE,1992, 80(1):163-172.
[20]Carter P S. Short Wave Antenna[P].1939, Oct.10:2,175,252.
[21]Lindenblad N E. Wide Band Antenna[P].1941, Apr.29:2,239,724.
[22]Paulsen L, West J B, Perger W F, et al. Recent Investigations on the Volcano Smoke Antenna[C]. Antenna and Propagation Society International Symposium, Columbus, Ohio,2003(3):845-848.
[23]Brillouin L N. Broad Band Antenna[P].1948, Nov.30:2,454,766.
[24]King A P. Transmission Radiation, and Reception of Electromagnetic Waves[P].1942, May 26:2,283,935.
[25]Schantz H G. A Brief History of UWB Antennas[C]. IEEE Conference on Ultra Wideband Systems and Technologies, Reston, Virginia, U.S.,2003:209-213.
[26]Brown G H, Woodward O M. Experimentally Determined Radiation Characteristics of Conical and Triangular Antennas[G]. RCA Review,1952 (13):425-452.
[27]Masters R W. Antenna[P].1947, Nov.4:2,430,353.
[28]Schantz H G, Fullerton L. The Diamond Dipole:A Gaussian Impulse Antenna[C]. Antenna and Propagation Society International Symposium, Boston, Massachusetts, U.S.,2001(4):100-103.
[29]Lalezari F, et al. Broadband Notch Antenna[P].1989, Jun.27:4,843,403.
[30]Thomas M, et al. Wideband Arrayable Planar Radiator[P].1994, Jun.7: 5,319,377.
[31]Marie G R P. Wide Band Slot Antenna[P].1962, Apr.24:3,031,665.
[32]Harmuth H. Frequency Independent Shielded Loop Antenna[P].1985, March 19:4,506,267.
[33]Barnes M. Ultra-Wideband Magnetic Antenna[P].2000, Jul.18:6,091,374.
[34]Barnes M. Ultra-Wideband Magnetic Antenna[P].2002, Jun.4:6,400,329.
[35]Wong M, Sebak A R. Dual Band Dual Slot Stripline Omni-directional Antenna[C]. IEEE 64th Vehicular Technology Conference, Montreal, Canada, 2006:1-4.
[36]Lin C C, Chuang H R. A 2.4GHz Omni-directional Horizontally Polarized Planar Printed Antenna for WLAN Applications[C]. Antenna and Propagation Society International Symposium, Columbus, Ohio, U.S.,2003(2):42-45.
[37]Hsu H T, Rautio J, Chang S W. Novel Planar Wideband Omni-directional Quasi Log-periodic Antenna[C]. Asia-Pacific Microwave Conference, Suzhou, China,2005(4):4.
[38]Zhang C, Fathy A E. Development of an Ultra-wideband Elliptical Disc Planar Monopole Antenna with Improved Omni-directional Performance Using a Modified Ground[C]. Antenna and Propagation Society International Symposium, Albuquerque, NM, U.S.,2006:1689-1692.
[39]Wu Q, Jin R H, Geng J P, et al. Printed Omni-directional UWB Monopole Antenna with Very Compact Size[J]. IEEE Transactions on Antennas and Propagation,2008,56(3):896-899.
[40]Wakabayashi T, Matsui H. Omni-directional Characteristics over Frequency Range for UWB of Modified Planar Antenna with an Elliptical Element on the Dielectric Substrate[C].6th International Symposium on Wireless Communication Systems, Tuscany, Italy,2009:463-467.
[41]Karim M A, Saeed F, Hadi A. Broadband Log-periodical Antenna with Omni-directional Radiation Pattern in the Horizontal Plane[C]. The Fourth European Conference on Antennas and Propagation, Barcelona, Spain,2010: 1-4.
[42]Gronich I. Omni Directional Ultra Wideband Asymmetric Biconical Antenna[C]. IEEE International Conference on Microwaves, Communications, Antennas and Electronics Systems,2009:1-4.
[43]Alipour A, Hassani H R. A Novel Omni-directional UWB Monopole Antenna[J]. IEEE Transactions on Antennas and Propagation,2008,56(12): 3854-3857.
[44]Chen S L, Mittra R. A Triple-feed and Near Omni-directional (3D) RFID Tag Antenna Design[C]. Asia-Pacific Microwave Conference, Singapore,2009: 2391-2393.
[45]Kaiwen K T, Qing X M, Chean K G, et al. A UHF Omni-directional RFID antenna[C]. Antenna and Propagation Society International Symposium, Toronto, Canada,2010:1-4.
[46]吴琦.新型超宽带天线研究[D].上海：上海交通大学博士学位论文,2009：6-10.
[47]Schantz H G. Introduction to Ultra-wideband Antennas[C]. IEEE Conference on Ultra Wideband Systems and Technologies, Reston, Virginia, U.S.,2003: 1-9.
[48]Shlivinski A, Heyman E, Kastner R. Antenna Characterization in the Time Domain[J]. IEEE Transactions on Antennas and Propagation,1997,45(7): 1140-1149.
[49]Stofar W. Broadband Ellipsoidal Dipole Antenna[P].1968, Jan.16:3,364,491.
[50]钟玲玲.超宽带圆片天线及其小型化[D].哈尔滨：哈尔滨工业大学博士学位论文,2008：35-38.
[2]McEwan T. Body Monitoring and Imaging Apparatus and Method[P].1994, Aug.9:5,573,012.
[3]Craddock I J, Klemm M, Leendertz J, et al. Development and Application of a UWB Radar System for Breast Imaging[C]. Antennas and Propagation Conference, Loughborough, UK,2008:24-27.
[4]Zhuge X, Savelyev T G, Yarovoy A G. Assessment of Electromagnetic Requirements for UWB Through-wall Radar[C]. International Conference on Electromagnetics in Advanced Applications, Torino, Italy,2007:923-926.
[5]Ossberger G, Buchegger T, Schimback E, et al. Non-invasive Respiratory Movement Detection and Monitoring of Hidden Humans Using Ultra Wideband Pulse Radar[C]. International Workshop on Ultra Wideband Systems Joint with Conference on Ultrawideband Systems and Technologies, Kyoto, Japan,2004:395-399.
[6]黎海涛.超宽带无线通信的进展[J].信息网络,2003,(8)：23-25.
[7]Chong C C, Watanabe F, Inamura H. Potential of UWB Technology for the Next Generation Wireless Communications[C]. IEEE Ninth International Symposium on Spread Spectrum Techniques and Applications, Manaus, Brazil, 2006:422-429.
[8]Martigne P. UWB for Low Data Rate Applications:Technology Overview and Regulatory Aspects[C]. IEEE International Symposium on Circuits and Systems, Island of Kos, Greece,2006:2428.
[9]Molisch A F, Balakrishnan K, Cassioli D, et al. IEEE 802.15.4a Channel Model-Final Report[R]. IEEE Document 15-04-662-004-004a.
[10]Mahfouz M R, Zhang C, Merkl B C, et al. Investigation of High-accuracy Indoor 3-D Positioning Using UWB Technology [J]. IEEE Transactions on Microwave Theory and Techniques,2008,56(6):1316-1330.
[11]Multispectral Solutions Inc.. Sapphire DART (RTLS) Product Data Sheet[EB/OL]. (2007). http://www.multispectral.com/pdf/Sapphire_DART. pdf.
[12]Ubisense. Hardware Datasheet(EB/OL). (2006). http://www.ubisense.net /SITE/UPLOAD/Document/TechDocs/Ubisense hardware datasheet May 20 06.pdf.
[13]Meier C, Terzis A, Lindenmeier S. A Robust 3-D High-precision Radio Location System[C]. IEEE/MTT-S International Microwave Symposium, Honolulu, Hawaii, U.S.,2007:397-400.
[14]Pozar D M. Closed-form Approximations for Link Loss in a UWB Radio System Using Small Antennas[J]. IEEE Transactions on Antennas and Propagation,2003,51(9):2346-2352.
[15]Hansen R C. Microwave scanning antennas:Vol Ⅱ. Array Theory and Practice. U.S.:Academic Press,1964.
[16]Mayes P E. Frequency-independent Antennas and Broad-band Derivative thereof[C]. Proceedings of the IEEE,1992,80(1):103-112.
[17]Schwering F K. Millimeter Wave Antennas[C]. Proceedings of the IEEE,1992, 80(1):92-102.
[18]Kummer W H. Basic Array Theory[C]. Proceedings of the IEEE,1992,80(1): 127-140.
[19]Mailloux R J. Antenna Array Architecture[C]. Proceedings of the IEEE,1992, 80(1):163-172.
[20]Carter P S. Short Wave Antenna[P].1939, Oct.10:2,175,252.
[21]Lindenblad N E. Wide Band Antenna[P].1941, Apr.29:2,239,724.
[22]Paulsen L, West J B, Perger W F, et al. Recent Investigations on the Volcano Smoke Antenna[C]. Antenna and Propagation Society International Symposium, Columbus, Ohio,2003(3):845-848.
[23]Brillouin L N. Broad Band Antenna[P].1948, Nov.30:2,454,766.
[24]King A P. Transmission Radiation, and Reception of Electromagnetic Waves[P].1942, May 26:2,283,935.
[25]Schantz H G. A Brief History of UWB Antennas[C]. IEEE Conference on Ultra Wideband Systems and Technologies, Reston, Virginia, U.S.,2003:209-213.
[26]Brown G H, Woodward O M. Experimentally Determined Radiation Characteristics of Conical and Triangular Antennas[G]. RCA Review,1952 (13):425-452.
[27]Masters R W. Antenna[P].1947, Nov.4:2,430,353.
[28]Schantz H G, Fullerton L. The Diamond Dipole:A Gaussian Impulse Antenna[C]. Antenna and Propagation Society International Symposium, Boston, Massachusetts, U.S.,2001(4):100-103.
[29]Lalezari F, et al. Broadband Notch Antenna[P].1989, Jun.27:4,843,403.
[30]Thomas M, et al. Wideband Arrayable Planar Radiator[P].1994, Jun.7: 5,319,377.
[31]Marie G R P. Wide Band Slot Antenna[P].1962, Apr.24:3,031,665.
[32]Harmuth H. Frequency Independent Shielded Loop Antenna[P].1985, March 19:4,506,267.
[33]Barnes M. Ultra-Wideband Magnetic Antenna[P].2000, Jul.18:6,091,374.
[34]Barnes M. Ultra-Wideband Magnetic Antenna[P].2002, Jun.4:6,400,329.
[35]Wong M, Sebak A R. Dual Band Dual Slot Stripline Omni-directional Antenna[C]. IEEE 64th Vehicular Technology Conference, Montreal, Canada, 2006:1-4.
[36]Lin C C, Chuang H R. A 2.4GHz Omni-directional Horizontally Polarized Planar Printed Antenna for WLAN Applications[C]. Antenna and Propagation Society International Symposium, Columbus, Ohio, U.S.,2003(2):42-45.
[37]Hsu H T, Rautio J, Chang S W. Novel Planar Wideband Omni-directional Quasi Log-periodic Antenna[C]. Asia-Pacific Microwave Conference, Suzhou, China,2005(4):4.
[38]Zhang C, Fathy A E. Development of an Ultra-wideband Elliptical Disc Planar Monopole Antenna with Improved Omni-directional Performance Using a Modified Ground[C]. Antenna and Propagation Society International Symposium, Albuquerque, NM, U.S.,2006:1689-1692.
[39]Wu Q, Jin R H, Geng J P, et al. Printed Omni-directional UWB Monopole Antenna with Very Compact Size[J]. IEEE Transactions on Antennas and Propagation,2008,56(3):896-899.
[40]Wakabayashi T, Matsui H. Omni-directional Characteristics over Frequency Range for UWB of Modified Planar Antenna with an Elliptical Element on the Dielectric Substrate[C].6th International Symposium on Wireless Communication Systems, Tuscany, Italy,2009:463-467.
[41]Karim M A, Saeed F, Hadi A. Broadband Log-periodical Antenna with Omni-directional Radiation Pattern in the Horizontal Plane[C]. The Fourth European Conference on Antennas and Propagation, Barcelona, Spain,2010: 1-4.
[42]Gronich I. Omni Directional Ultra Wideband Asymmetric Biconical Antenna[C]. IEEE International Conference on Microwaves, Communications, Antennas and Electronics Systems,2009:1-4.
[43]Alipour A, Hassani H R. A Novel Omni-directional UWB Monopole Antenna[J]. IEEE Transactions on Antennas and Propagation,2008,56(12): 3854-3857.
[44]Chen S L, Mittra R. A Triple-feed and Near Omni-directional (3D) RFID Tag Antenna Design[C]. Asia-Pacific Microwave Conference, Singapore,2009: 2391-2393.
[45]Kaiwen K T, Qing X M, Chean K G, et al. A UHF Omni-directional RFID antenna[C]. Antenna and Propagation Society International Symposium, Toronto, Canada,2010:1-4.
[46]吴琦.新型超宽带天线研究[D].上海：上海交通大学博士学位论文,2009：6-10.
[47]Schantz H G. Introduction to Ultra-wideband Antennas[C]. IEEE Conference on Ultra Wideband Systems and Technologies, Reston, Virginia, U.S.,2003: 1-9.
[48]Shlivinski A, Heyman E, Kastner R. Antenna Characterization in the Time Domain[J]. IEEE Transactions on Antennas and Propagation,1997,45(7): 1140-1149.
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