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Wide-angle scanning linear phased arrays based on wide-beam magneto electric dipole antenna

Yan Hao-Nan Cao Xiang-Yu Gao Jun Yang Huan-Huan Li Tong

Wide-angle scanning linear phased arrays based on wide-beam magneto electric dipole antenna

Yan Hao-Nan, Cao Xiang-Yu, Gao Jun, Yang Huan-Huan, Li Tong
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  • Microstrip phased array has aroused interest of many researchers because of its beam agility. However, a big problem for typical microstrip array is that its main beam can only scan from about –50° to 50°, with a gain loss of 4-5 dB. Meanwhile, the relatively narrow operating bandwidth of microstrip antenna is also a problem in application. These flaws have dramatically limited its applications and spawned many studies on phased array with wide-angle scanning capability. Several methods have been proposed to broaden the scanning coverage of phased array, such as utilizing pattern-reconfigurable antenna as an element of array, taking wide-beam antenna as the element of array, and adopt metasurface as the top cladding of array. However, most of existing researches mainly focus on achieving wide-angle scanning performance within a relatively narrow bandwidth. A phased array that possesses wide-angle scanning capability at both main planes within a relatively wide bandwidth is highly desirable. In this paper, a wide-beam magnetoelectric (ME) dipole antenna is proposed. It consists of an ME dipole antenna in the form of microstrip patch and a pair of magnetic dipoles. Metallic through holes integrated with patches and ground are utilized to form magnetic currents. Extra magnetic dipoles are added to broaden the 3-dB beam-width. The simulated results reveal that the 3-dB beam-width of the proposed antenna is greater than 107° in the E-plane (9 GHz–12 GHz) and 178° in the H-plane (7 GHz–12 GHz) respectively. The impedance bandwidth of the proposed antenna is 53.26% from 7.3 GHz to 12.6 GHz (VWSR < 2). Based on the proposed antenna element, two linear phased arrays are fabricated and measured. To test the wide-angle scanning capability of the arrays, each antenna element is simply fed with alternating currents with identical amplitude and linearly increasing phases. The measured results reveal that the wide-angle scanning capability of H-plane array and E-plane array can be obtained from 9 GHz to 12 GHz. The scanning beam of the H-plane array can cover the range from -90° to 90°. The scanning beam of the E-plane array can cover the range from –70° to 70°. The impedance bandwidth of the central antenna is 27.03% for the H-plane array from 9.6 GHz to 12.6 GHz (active VWSR < 2.5) and 36.36% for the E-plane array from 9 GHz to 13 GHz (active VWSR < 2) respectively. Hence, the proposed method can be used as a reference for designing a wide-beam antenna and wide-angle scanning phased array and the designed phased arrays can be applied to X-band radar systems.
      Corresponding author: Yan Hao-Nan, 18220526812@163.com
    [1]

    张祖稷, 金林, 束咸荣 2005 雷达天线技术 (北京: 电子工业出版社) 第221页

    Zhang Z J, Jin L, Shu X R 2007 Radar Antenna Technology (Beijing: Publishing House of Electronics Industry) p221 (in Chinese)

    [2]

    Bai Y Y, Xiao S Q, Wang B Z, Ding Z F 2010 J. Infrared Millim. Terahertz Waves 31 1

    [3]

    Bai Y Y, Xiao S Q, Tang M C, Ding Z F 2011 IEEE Trans. Antennas Propag. 59 4071

    [4]

    Ding X, Wang B Z, He G Q 2013 IEEE Trans. Antennas Propag. 61 5319

    [5]

    Xiao S Q, Zheng C R, Li M, Xiong J 2015 IEEE Trans. Antennas Propag. 63 2364

    [6]

    Cheng Y F, Ding X, Shao W, Yu M X, Wang B Z 2017 IEEE Antennas Wireless Propag. Lett. 16 396

    [7]

    Ding X, Cheng Y F, Shao W, Wang B Z 2017 IEEE Trans. Antennas Propag. 65 4548

    [8]

    Ge L, Luk K M 2015 IEEE Antennas Wireless Propag. Lett. 14 28

    [9]

    Ge L, Luk K M 2016 IEEE Trans. Antennas Propag. 64 423

    [10]

    Shi Y, Cai Y, Yang J, Li L 2019 IEEE Antennas Wireless Propag. Lett. 18 28

    [11]

    Lin G 2007 Radar Sci. Technol. 5 157

    [12]

    Wang R, Wang B Z, Hu C, Ding X 2015 IEEE Trans. Antennas Propag. 63 3908

    [13]

    Wang R, Wang B Z, Ding X, Yang X S 2017 Sci. Rep. 7 2729

    [14]

    Liu C M, Xiao S Q, Tu H L, Ding Z F 2017 IEEE Trans. Antennas Propag. 65 1151

    [15]

    Cheng Y F, Ding X, Shao W, Yu M X, Wang B Z 2017 IEEE Antennas Wireless Propag. Lett. 16 876

    [16]

    Yang G W, Li J Y, Wei D J, Xu R 2018 IEEE Trans. Antennas Propag. 66 450

    [17]

    Yang G W, Li J Y, Yang J J, Zhou S G 2018 IEEE Trans. Antennas Propag. 66 6724

    [18]

    Yang G W, Chen Q Q, Li J Y, Zhou S G, Xing Z J 2019 IEEE Acc. 7 71897

    [19]

    Chattopadhyay S 2009 IEEE Trans. Antennas Propag. 57 3325

    [20]

    Yang H H, Li T, Xu L M, Cao X Y, Gao J, Tian J H, Yang H N, Sun D 2019 IEEE Acc. 7 152715

    [21]

    Lü Y H, Ding X, Wang B Z, Anagnostou D E 2020 IEEE Trans. Antennas Propag. 68 1402

    [22]

    Luk K M, Wong H 2006 Int. J. Microw. Opt. Technol. 1 35

    [23]

    Ng K B, Wong H, So K K, Chan C H, Luk K M 2012 IEEE Trans. Antennas Propag. 60 3129

    [24]

    Li Y J, Luk K M 2014 IEEE Trans. Antennas Propag. 62 1830

    [25]

    Lai J, Feng B, Zeng Q 2019 IEEE 6th International Symposium on Electromagnetic Compatibility Nanjing, China November 1–4, 2019 p1

    [26]

    Feng B T, Zhu C, Cheng J C, Sim C Y D 2019 IEEE Acc. 7 43346

    [27]

    郑贵 2016 硕士学位论文 (成都: 电子科技大学)

    Zheng G 2016 M. S. Thesis (Chengdu: University of Electronic Science and Technology of China) (in Chinese)

    [28]

    王茂泽 2014 硕士学位论文 (西安: 西安电子科技大学)

    Wang M Z 2014 M. S. Thesis (Xi’an: Xidian University) (in Chinese)

    [29]

    徐志 2008 博士学位论文 (西安: 西安电子科技大学)

    Xu Z 2008 Ph. D. Dissertation (Xi’an: Xidian University) (in Chinese)

    [30]

    Smolders A B 1996 Proceedings of International Symposium on Phased Array Systems and Technology Boston, MA, USA, October 15–18, 1996 p87

    [31]

    Kedar A, Beenamole K S 2011 Prog. Electro. Res. B 27 235

  • 图 1  宽波束天线单元结构图 (a) 三维图; (b) 俯视图

    Figure 1.  Structure of the wide-beam antenna: (a) 3-D view; (b) top view.

    图 2  设计流程

    Figure 2.  The design process.

    图 3  10 GHz处3-dB波束宽度拓展效果

    Figure 3.  The broadening effect of 3-dB beam-width at 10 GHz.

    图 4  10 GH处电流分布图 (a) 0°; (b) 90°; (a) 180°; (b) 270°

    Figure 4.  The distribution of electric current at 10 GHz: (a) 0°; (b) 90°; (c) 180°; (d) 270°.

    图 5  天线单元驻波比

    Figure 5.  VSWR of the antenna.

    图 6  天线单元方向图

    Figure 6.  Radiation patterns of the antenna.

    图 7  一维相控阵列 (a) E面阵列; (b) H面阵列

    Figure 7.  The phased arrays: (a) E-plane array; (b) H-plane array.

    图 8  阵列实物图 (a) E面阵列; (b) H面阵列

    Figure 8.  The prototypes of the arrays: (a) E-plane array; (b) H-plane array.

    图 9  阵列中心单元实测有源驻波比 (a) E面阵列; (b) H面阵列

    Figure 9.  The active VSWRs of the unit at the center of two arrays: (a) E-plane array; (b) H-plane array.

    图 10  E面阵列实测扫描方向图 (a) 9 GHz; (b) 10 GHz; (a) 11 GHz; (b) 12 GHz

    Figure 10.  The scanning patterns of the E-plane array: (a) 9 GHz; (b) 10 GHz; (c) 11 GHz; (d) 12 GHz.

    图 11  H面阵列实测扫描方向图 (a) 9 GHz; (b) 10 GHz; (a) 11 GHz; (b) 12 GHz

    Figure 11.  The scanning patterns of the H-plane array: (a) 9 GHz; (b) 10 GHz; (c) 11 GHz; (d) 12 GHz.

    表 1  宽波束天线单元参数

    Table 1.  Parameters of the wide-beam antenna.

    天线参数LWHL1L2L3L4L5L6 L7L8W1W2W3W4W5W6W7
    参数值/mm1593.50.63.22.221.50.5 3.21.551.51.52.8621
    DownLoad: CSV

    表 2  天线单元3-dB波束宽度

    Table 2.  3-dB beam-width of the antenna.

    频率/GHzE面3-dB波束宽度/(°)H面3-dB波束宽度/(°)
    797180.4
    8101.1178.2
    9107178.4
    10115.8185.2
    11135.5220.9
    12180.6360
    DownLoad: CSV

    表 3  2号天线与3号天线增益对比

    Table 3.  Comparison between Ant.2 and Ant.3.

    频率/GHz参考天线增益/dBi本文天线增益-/dBi
    95.914.19
    105.983.91
    115.843.59
    125.432.87
    DownLoad: CSV

    表 4  已报道宽波束磁电偶极子天线与本文天线特性对比

    Table 4.  Comparison between the reported and proposed magneto-electric dipole antenna.

    文献相对阻抗带宽/%工作频带/GHz增益/dBi剖面/λE面波束宽度/(°)H面波束宽度/(°)
    [16]34.63.1—4.40.21174112
    [17]81.13.3—7.83.65 ± 1.650.27215 (5.5 GHz)
    106 (7.5 GHz)
    186 (5.5 GHz)
    83 (7.5 GHz)
    [24]412.42—3.76.30.4575120
    [25]632.76—5.350.15129.1 (3.4 GHz)
    151.6 (4.9 GHz)
    100.4 (3.4 GHz)
    94.2 (4.9 GHz)
    [26]22.6
    19.6
    3.25—4.08
    4.29—5.22
    6.9 ± 0.3
    5.4 ± 0.7
    0.27
    0.23
    91 (3.5 GHz)
    168 (4.9 GHz)
    83 (3.5 GHz)
    74 (4.9 GHz)
    83 (3.5 GHz)
    162 (4.9 GHz)
    90 (3.5 GHz)
    133 (4.9 GHz)
    本文53.267.3—12.63.53 ± 0.660.116>97>178.2
    DownLoad: CSV

    表 5  已报道X波段相控阵与本文相控阵天线特性对比

    Table 5.  Comparison between the reported and proposed X-band phased arrays.

    文献相对阻抗带宽/%工作频带/GHz剖面/λE面扫描范围/(°)H面扫描范围/(°)
    [27]408—120.31± 60 (8—10 GHz)
    ± 50 (12 GHz)
    ± 60 (8—10 GHz)
    ± 50 (12 GHz)
    [28]408—121.22± 45± 45
    [29]18.1810.5—12.60.84± 60± 60
    [30]408—120.8± 45± 60
    [31]30± 60± 60
    本文28.59—120.116± 70± 90
    DownLoad: CSV
  • [1]

    张祖稷, 金林, 束咸荣 2005 雷达天线技术 (北京: 电子工业出版社) 第221页

    Zhang Z J, Jin L, Shu X R 2007 Radar Antenna Technology (Beijing: Publishing House of Electronics Industry) p221 (in Chinese)

    [2]

    Bai Y Y, Xiao S Q, Wang B Z, Ding Z F 2010 J. Infrared Millim. Terahertz Waves 31 1

    [3]

    Bai Y Y, Xiao S Q, Tang M C, Ding Z F 2011 IEEE Trans. Antennas Propag. 59 4071

    [4]

    Ding X, Wang B Z, He G Q 2013 IEEE Trans. Antennas Propag. 61 5319

    [5]

    Xiao S Q, Zheng C R, Li M, Xiong J 2015 IEEE Trans. Antennas Propag. 63 2364

    [6]

    Cheng Y F, Ding X, Shao W, Yu M X, Wang B Z 2017 IEEE Antennas Wireless Propag. Lett. 16 396

    [7]

    Ding X, Cheng Y F, Shao W, Wang B Z 2017 IEEE Trans. Antennas Propag. 65 4548

    [8]

    Ge L, Luk K M 2015 IEEE Antennas Wireless Propag. Lett. 14 28

    [9]

    Ge L, Luk K M 2016 IEEE Trans. Antennas Propag. 64 423

    [10]

    Shi Y, Cai Y, Yang J, Li L 2019 IEEE Antennas Wireless Propag. Lett. 18 28

    [11]

    Lin G 2007 Radar Sci. Technol. 5 157

    [12]

    Wang R, Wang B Z, Hu C, Ding X 2015 IEEE Trans. Antennas Propag. 63 3908

    [13]

    Wang R, Wang B Z, Ding X, Yang X S 2017 Sci. Rep. 7 2729

    [14]

    Liu C M, Xiao S Q, Tu H L, Ding Z F 2017 IEEE Trans. Antennas Propag. 65 1151

    [15]

    Cheng Y F, Ding X, Shao W, Yu M X, Wang B Z 2017 IEEE Antennas Wireless Propag. Lett. 16 876

    [16]

    Yang G W, Li J Y, Wei D J, Xu R 2018 IEEE Trans. Antennas Propag. 66 450

    [17]

    Yang G W, Li J Y, Yang J J, Zhou S G 2018 IEEE Trans. Antennas Propag. 66 6724

    [18]

    Yang G W, Chen Q Q, Li J Y, Zhou S G, Xing Z J 2019 IEEE Acc. 7 71897

    [19]

    Chattopadhyay S 2009 IEEE Trans. Antennas Propag. 57 3325

    [20]

    Yang H H, Li T, Xu L M, Cao X Y, Gao J, Tian J H, Yang H N, Sun D 2019 IEEE Acc. 7 152715

    [21]

    Lü Y H, Ding X, Wang B Z, Anagnostou D E 2020 IEEE Trans. Antennas Propag. 68 1402

    [22]

    Luk K M, Wong H 2006 Int. J. Microw. Opt. Technol. 1 35

    [23]

    Ng K B, Wong H, So K K, Chan C H, Luk K M 2012 IEEE Trans. Antennas Propag. 60 3129

    [24]

    Li Y J, Luk K M 2014 IEEE Trans. Antennas Propag. 62 1830

    [25]

    Lai J, Feng B, Zeng Q 2019 IEEE 6th International Symposium on Electromagnetic Compatibility Nanjing, China November 1–4, 2019 p1

    [26]

    Feng B T, Zhu C, Cheng J C, Sim C Y D 2019 IEEE Acc. 7 43346

    [27]

    郑贵 2016 硕士学位论文 (成都: 电子科技大学)

    Zheng G 2016 M. S. Thesis (Chengdu: University of Electronic Science and Technology of China) (in Chinese)

    [28]

    王茂泽 2014 硕士学位论文 (西安: 西安电子科技大学)

    Wang M Z 2014 M. S. Thesis (Xi’an: Xidian University) (in Chinese)

    [29]

    徐志 2008 博士学位论文 (西安: 西安电子科技大学)

    Xu Z 2008 Ph. D. Dissertation (Xi’an: Xidian University) (in Chinese)

    [30]

    Smolders A B 1996 Proceedings of International Symposium on Phased Array Systems and Technology Boston, MA, USA, October 15–18, 1996 p87

    [31]

    Kedar A, Beenamole K S 2011 Prog. Electro. Res. B 27 235

  • Citation:
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  • Abstract views:  543
  • PDF Downloads:  30
  • Cited By: 0
Publishing process
  • Received Date:  12 July 2020
  • Accepted Date:  11 August 2020
  • Available Online:  12 January 2021
  • Published Online:  05 January 2021

Wide-angle scanning linear phased arrays based on wide-beam magneto electric dipole antenna

    Corresponding author: Yan Hao-Nan, 18220526812@163.com
  • Information and Navigation College, Air Force Engineering University, Xi’an 710077, China

Abstract: Microstrip phased array has aroused interest of many researchers because of its beam agility. However, a big problem for typical microstrip array is that its main beam can only scan from about –50° to 50°, with a gain loss of 4-5 dB. Meanwhile, the relatively narrow operating bandwidth of microstrip antenna is also a problem in application. These flaws have dramatically limited its applications and spawned many studies on phased array with wide-angle scanning capability. Several methods have been proposed to broaden the scanning coverage of phased array, such as utilizing pattern-reconfigurable antenna as an element of array, taking wide-beam antenna as the element of array, and adopt metasurface as the top cladding of array. However, most of existing researches mainly focus on achieving wide-angle scanning performance within a relatively narrow bandwidth. A phased array that possesses wide-angle scanning capability at both main planes within a relatively wide bandwidth is highly desirable. In this paper, a wide-beam magnetoelectric (ME) dipole antenna is proposed. It consists of an ME dipole antenna in the form of microstrip patch and a pair of magnetic dipoles. Metallic through holes integrated with patches and ground are utilized to form magnetic currents. Extra magnetic dipoles are added to broaden the 3-dB beam-width. The simulated results reveal that the 3-dB beam-width of the proposed antenna is greater than 107° in the E-plane (9 GHz–12 GHz) and 178° in the H-plane (7 GHz–12 GHz) respectively. The impedance bandwidth of the proposed antenna is 53.26% from 7.3 GHz to 12.6 GHz (VWSR < 2). Based on the proposed antenna element, two linear phased arrays are fabricated and measured. To test the wide-angle scanning capability of the arrays, each antenna element is simply fed with alternating currents with identical amplitude and linearly increasing phases. The measured results reveal that the wide-angle scanning capability of H-plane array and E-plane array can be obtained from 9 GHz to 12 GHz. The scanning beam of the H-plane array can cover the range from -90° to 90°. The scanning beam of the E-plane array can cover the range from –70° to 70°. The impedance bandwidth of the central antenna is 27.03% for the H-plane array from 9.6 GHz to 12.6 GHz (active VWSR < 2.5) and 36.36% for the E-plane array from 9 GHz to 13 GHz (active VWSR < 2) respectively. Hence, the proposed method can be used as a reference for designing a wide-beam antenna and wide-angle scanning phased array and the designed phased arrays can be applied to X-band radar systems.

    • 相控阵天线因其波束捷变特性在军事雷达领域及民用通信领域具有广阔的应用前景, 引起了学界的广泛关注. 微带阵列天线因其具有剖面低、易加工及易与载体共形等优点已成为相控阵天线的主流形式. 然而, 对于微带相控阵列天线而言, 其主波束扫描范围仅为 ± 50°, 且扫描过程中增益会下降4—5 dB[1]. 同时, 微带相控阵列天线的工作带宽在实际应用中也有很大问题. 这些缺点限制了微带相控阵列天线的应用范围, 同时, 也引起了学界对于宽带宽角扫描相控阵列天线的广泛研究.

      近年来, 学界提出了几种拓展相控阵列扫描范围的方法. 第一种方法是利用方向图可重构天线单元作为阵元[2-7]. 天线单元的3-dB波束宽度并不是非常宽, 但是可以通过改变天线单元辐射方向图进行波束切换, 进而实现宽角扫描.同时, 学界对于方向图可重构磁电偶极子天线单元进行了深入研究, 如H面波束宽度可重构磁电偶极子天线[8,9], 双面波束宽度可重构磁电偶极子天线[10]. 上述波束宽度可调的磁电偶极子天线在宽角扫描阵列的设计中应用前景广阔. 然而, 这类天线单元引入了额外的电子元件及控制电路, 从而增加了设计难度, 并对辐射方向图产生了不良影响.

      与利用方向图可重构天线单元作为阵元不同, 另一类拓展相控阵列天线扫描范围的方法是采用宽波束天线单元作为阵元. 学界提出了多种拓展天线单元3-dB波束宽度的方法[11-19], 如新型微带磁偶极子天线[14]、 采用寄生像素层[15]以及使用电壁[16,17]. 值得注意的是, 文献[12]将常见的载体天线分为八类并指出了具有宽角扫描应用潜力的天线单元类型, 从而为设计宽波束天线提供了指导思路. 采用宽波束天线作为阵元使得阵列天线旁瓣水平升高, 文献[20]中的布阵策略可为解决这些问题提供参考.

      常见的拓展相控阵列天线扫描范围的方法还包括利用梯度超表面[21]作为阵列覆层. 当阵列发射电磁波透过特定设计的梯度超表面时, 波束偏转至更低角域, 从而拓展了阵列扫描范围.

      就上述文献而言, 大多数研究集中于某个频点附近, 也就是说, 所设计的相控阵列天线仅能在点频范围内实现宽角扫描, 而对于能够在宽带范围内实现宽角扫描的相控阵列天线研究不足, 而这也正是实际应用亟需的.

      本文设计并测试了两款基于宽波束天线单元的宽角扫描线性阵列. 首先, 通过加载微带磁偶极子的方法拓展了天线单元的3-dB波束宽度. 基于此, 设计了两款9单元一维扫描阵列并进行了加工测试. 仿真和实测结果均表明, 加载的微带磁偶极子有效拓展了天线单元的3-dB波束宽度, 所设计的一维阵列天线具备在宽频带范围内实现宽角扫描的能力.

    2.   宽波束天线单元结构的设计与分析
    • 本文提出的宽波束天线单元主要由两部分组成(图1). 第一部分为微带磁电偶极子天线, 该结构与文献[22]中设计的天线类似, 通过介质板集成金属化过孔技术获得磁偶极子, 水平辐射贴片则充当电偶极子. 介质基板介电常数为4.4, 损耗角正切为0.0025. 第二部分为用来拓展天线3-dB波束宽度而加载的微带磁偶极子, 表1给出了天线单元的详细结构参数.

      Figure 1.  Structure of the wide-beam antenna: (a) 3-D view; (b) top view.

      天线参数LWHL1L2L3L4L5L6 L7L8W1W2W3W4W5W6W7
      参数值/mm1593.50.63.22.221.50.5 3.21.551.51.52.8621

      Table 1.  Parameters of the wide-beam antenna.

      天线单元的宽带特性是宽带阵列的前提. 文献[23]中提出的磁电偶极子天线是一款结构简单、辐射性能稳定的宽带天线. 天线单元的宽波束特性可通过加载微带磁偶极子实现. 图2展示了宽波束天线单元的设计流程. 首先, 改变了文献[22]中天线的尺寸, 使其工作于X波段, 得到1号天线. 然后, 改变了1号天线的馈电结构及电偶极子的形状以获得更好的阻抗匹配特性, 得到2号天线. 利用电磁仿真软件Ansys HFSS对2号天线单元进行仿真, 计算其波束宽度.图3给出了其在10 GHz下的辐射方向图. 由图3可知, 2号天线单元E面方向图3-dB波束宽度仅为82.3°, 未能达到希望的波束宽度100°, 不能满足宽角扫描相控阵列天线的设计要求. 为拓展天线波束宽度, 在电偶极子两侧加载了微带磁偶极子. 由图3可得, 加载微带磁偶极子的3号天线, 其E面3-dB波束宽度由82.3°拓宽至115.8°, H面3-dB波束宽度由119.8°拓宽至185.2°.

      Figure 2.  The design process.

      Figure 3.  The broadening effect of 3-dB beam-width at 10 GHz.

      图4给出了3号天线单元10 GHz处一个周期内的表面电流分布图. 由图4可知, 新增加的金属化过孔表面电流与同侧原有金属过孔表面电流方向相同, 从而在原有等效磁流M2的基础上增加了两个等效磁流M1M3. 磁流平行于金属的模型可用镜像原理分析. 基于文献[12]对常见载体天线的分类, “磁流平行于电壁”类天线在上半空间拥有近乎全向的方向图. 新引入的等效磁流加强了天线在低仰角区域的辐射, 从而拓展了天线的方向图波束宽度.

      Figure 4.  The distribution of electric current at 10 GHz: (a) 0°; (b) 90°; (c) 180°; (d) 270°.

      图5给出了设计的宽波束天线单元的驻波比. 由图5可得, 设计的天线单元在7.3—12.6 GHz驻波比小于2, 相对阻抗带宽为53.26%. 图6给出了设计的宽波束天线单元在7—12 GHz的辐射方向图, 表2给出了天线单元在该频带范围内的3-dB波束宽度. 由表2可得, 天线单元的E面方向图3-dB波束宽度在9—12 GHz均大于107°, H面方向图3-dB波束宽度在9—GHz均大于178°. 综合驻波比及3-dB波束宽度来看, 提出的天线单元已满足宽带宽角扫描相控阵列对于天线单元的设计要求. 然而, 波束展宽后, 天线单元的增益下降. 表3给出了参考天线及波束展宽后天线的增益数值.

      频率/GHzE面3-dB波束宽度/(°)H面3-dB波束宽度/(°)
      797180.4
      8101.1178.2
      9107178.4
      10115.8185.2
      11135.5220.9
      12180.6360

      Table 2.  3-dB beam-width of the antenna.

      频率/GHz参考天线增益/dBi本文天线增益-/dBi
      95.914.19
      105.983.91
      115.843.59
      125.432.87

      Table 3.  Comparison between Ant.2 and Ant.3.

      Figure 5.  VSWR of the antenna.

      Figure 6.  Radiation patterns of the antenna.

      将所提出的天线和目前已有的具有宽波束特性的磁电偶极子天线进行了对比(表4), 由表4可得, 本文所设计的磁电偶极子天线主要优势在于双面宽波束特性、宽带特性及低剖面特性.

      文献相对阻抗带宽/%工作频带/GHz增益/dBi剖面/λE面波束宽度/(°)H面波束宽度/(°)
      [16]34.63.1—4.40.21174112
      [17]81.13.3—7.83.65 ± 1.650.27215 (5.5 GHz)
      106 (7.5 GHz)
      186 (5.5 GHz)
      83 (7.5 GHz)
      [24]412.42—3.76.30.4575120
      [25]632.76—5.350.15129.1 (3.4 GHz)
      151.6 (4.9 GHz)
      100.4 (3.4 GHz)
      94.2 (4.9 GHz)
      [26]22.6
      19.6
      3.25—4.08
      4.29—5.22
      6.9 ± 0.3
      5.4 ± 0.7
      0.27
      0.23
      91 (3.5 GHz)
      168 (4.9 GHz)
      83 (3.5 GHz)
      74 (4.9 GHz)
      83 (3.5 GHz)
      162 (4.9 GHz)
      90 (3.5 GHz)
      133 (4.9 GHz)
      本文53.267.3—12.63.53 ± 0.660.116>97>178.2

      Table 4.  Comparison between the reported and proposed magneto-electric dipole antenna.

    3.   一维宽角扫描阵列设计
    • 图7给出了一维宽角扫描阵列的模型图. 设计的阵列均为9单元线性阵列.考虑到栅瓣抑制条件及阵中单元有源驻波比, E面阵列阵元间距选定为12 mm, H面阵列阵元间距选定为9 mm.

      Figure 7.  The phased arrays: (a) E-plane array; (b) H-plane array.

    4.   加工与实测
    • 为检验设计方法的有效性, 对设计的一维线性扫描阵列进行了加工实测. 图8给出了加工样品的实物图.

      Figure 8.  The prototypes of the arrays: (a) E-plane array; (b) H-plane array.

      阵列中心单元的有源驻波比由安捷伦N5230 C矢量网络分析仪测试得到, 阵列的扫描方向图通过合成阵列中所有阵元的有源方向图得到, 因此, 实际测量过程中没有用到移相器及馈电网络, 仅通过微波暗室中的远场方向图测量系统测量得到了阵列中每一天线单元的有源方向图.

      图9给出了阵列中心天线单元的实测有源驻波比. 由图9可得, E面阵列中心单元有源驻波比在9—13 GHz小于2. 与仿真结果相比, 实测有源驻波比在10.3—11 GHz有所抬升, 但仍小于2. H面阵列中心单元的有源驻波比, 而在9.6—12.6 GHz小于2.5, 实测结果与仿真结果吻合较好.

      Figure 9.  The active VSWRs of the unit at the center of two arrays: (a) E-plane array; (b) H-plane array.

      图10给出了E面阵列的实测扫描方向图. 由图10可得, E面阵列的扫描波束可覆盖 ± 70°的角域范围, 扫描过程中天线增益损耗小于3 dB. 实测结果与仿真结果吻合较好, 验证了E面阵列的扫描性能.

      Figure 10.  The scanning patterns of the E-plane array: (a) 9 GHz; (b) 10 GHz; (c) 11 GHz; (d) 12 GHz.

      图11给出了H面阵列的实测扫描方向图. 由图11可得, H面阵列的扫描波束可覆盖 ± 90°的角域范围. 扫描过程中天线增益损耗小于2 dB. 实测结果与仿真结果吻合较好, 验证了H面阵列的扫描性能.

      Figure 11.  The scanning patterns of the H-plane array: (a) 9 GHz; (b) 10 GHz; (c) 11 GHz; (d) 12 GHz.

      将本文提出的相控阵和已发表的代表性X波段相控阵天线的典型指标进行了对比(表5), 由表5可得, 本文所设计的相控阵主要优势在于宽角扫描能力及低剖面特性.

      文献相对阻抗带宽/%工作频带/GHz剖面/λE面扫描范围/(°)H面扫描范围/(°)
      [27]408—120.31± 60 (8—10 GHz)
      ± 50 (12 GHz)
      ± 60 (8—10 GHz)
      ± 50 (12 GHz)
      [28]408—121.22± 45± 45
      [29]18.1810.5—12.60.84± 60± 60
      [30]408—120.8± 45± 60
      [31]30± 60± 60
      本文28.59—120.116± 70± 90

      Table 5.  Comparison between the reported and proposed X-band phased arrays.

    5.   结 论
    • 本文设计了一款宽波束磁电偶极子天线单元, 通过加载磁偶极子的方法拓展了天线的3-dB波束宽度, 基于该天线单元, 设计并测试了两款宽角扫描阵列. 实测结果表明, 设计的一维扫描阵列可在9 GHz—12 GHz实现有效宽角扫描. 因此, 本文所提出的加载磁偶极子的方法可为设计宽波束天线及宽角扫描阵列提供参考, 所设计的一维宽角扫描阵列在X波段相控阵雷达方面具有广阔的应用前景.

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