宽带定向天线及阵列研究

发布时间：2018-04-22 19:58

本文选题：宽带多频带微带天线 + 宽带电磁偶极子天线　；参考：《西安电子科技大学》2016年博士论文

【摘要】：随着无线通信系统的飞速发展,对系统中天线的结构和性能提出了越来越高的要求。一方面,由于定向性天线具有良好的方向性,在通信、雷达、广播、导航、探测等电子设备中有着广泛的需求和应用。另一方面,为了实现某些特定的需求,要求天线具有较高的增益和波束扫描特性,而传统的高增益波束可控阵列,譬如抛物面天线和相控阵,往往存在低性能或高成本的缺点,因此迫切需要基于新波束控制形式的高增益天线阵列。本文以宽带定向天线为主线,分别对微带天线、电磁偶极子天线和准八木印刷端射天线在内的三类天线做了研究,同时提出了一种具有广阔应用前景的新型波束可控阵列。本文的主要研究内容和贡献概括如下：1. 对微带天线的宽频带和多频带技术研究。首先,通过将半椭圆寄生贴片和空气介质结合,设计了一款相对阻抗带宽达到28.1%的宽频带微带天线,天线在带内增益稳定在8.0±1.0 dBi之间；其次,通过巧妙的激励方式,设计了双频微带天线,天线能工作在13.0 GHz和18.0 GHz附近,相对带宽分别达到10.0%和22.3%；最后,在双频带天线的基础上,通过增加F-形枝节设计了四频带微带天线,分别为6.9-7.3GHz、12.4-13.2 GHz、14.3-14.8 GHz和17.7-21.0 GHz,天线在各频带内增益不低于6.0 dBi,显示了良好的定向辐射特性,测试结果验证了设计的正确性。2. 提出了基于垂直结构的电磁偶极子天线。天线采用印刷结构的扇形偶极子和半圆环金属覆层分别作为电偶极子和磁偶极子,为了实现天线的宽带阻抗匹配特性,利用由微带线到共面带线巴伦同时激励电偶极子和磁偶极子,测试结果显示天线驻波比小于2的工作带宽为2.45-4.90 GHz,但是仿真及测试显示天线工作在高频时,辐射方向图会出现裂瓣,为了改善这一现象,设计了高折射率人工电磁材料,该材料由普通的介质材料加载H-形谐振器构成,通过将该材料加载于垂直结构的电磁偶极子前端,显著的改善了天线在高频的辐射方向图特性和增益,实测结果显示改进后天线的工作频带为2.31-3.93 GHz,且增益稳定在7.4-9.7 dBi之间。最后,以该单元为基础,做不同规模和形式的组阵仿真设计,仿真结果显示该单元具有良好的电磁特性和结构特性,具有一定的实用价值。3. 对准八木印刷端射天线进行了研究。提出了三种宽频带印刷端射天线。首先,利用微带线到共面带线巴伦的宽频带工作特性,设计了尺寸仅为24.24 mm×30 mm的印刷端射天线,该天线在S波段驻波比小于1.5的相对阻抗带宽达到75%,且在带内具有良好的端射辐射特性；其次,以印刷单极子天线为基础,通过增加引向器和反射器设计了具有端射辐射特性的宽带端射天线；最后,通过改进引向器的结构,在不增加天线尺寸的前提下,进一步增加了天线的工作带宽和辐射特性。4. 提出了一种新的波束可控阵列。该阵列以圆极化螺旋天线为基础,通过控制阵列中螺旋天线单元的不同旋转角度,能实现阵列中单元之间的相位差,从而实现阵列不同波束的切换。为了验证该理论,设计并加工了一个由128个圆极化螺旋天线单元构成的阵列,该阵列由1分128的等幅同相带状线馈电网络激励,同时为了实现波束切换,基于单元旋转方式设计了四幅阵面,分别为和波束阵面、差波束阵面、10。扫描波束阵面和平顶波束阵面,通过将四幅阵面分别与馈电网络连接并测试,测试结果与设计结果吻合较好,验证了该理论及方法的可行性。考虑到该波束控制阵列不需要移相器等电子元件,大大降低了阵列设计成本,因此可以预见,通过进一步完善阵列结构,该波束可控阵列将具有很大的市场应用价值。
[Abstract]:With the rapid development of the wireless communication system , the structure and performance of the antenna in the system are more and more demanding . On the other hand , because the directional antenna has good directivity , it has a wide demand and application in the electronic equipment such as communication , radar , broadcast , navigation and detection . A broadband microstrip antenna with a relative impedance bandwidth of 28.1 % is designed by combining semi - elliptic parasitic patch with air medium .
Secondly , the dual - band microstrip antenna is designed by smart excitation . The antenna can operate in the vicinity of 13.0 GHz and 18.0 GHz , with the relative bandwidth of 10.0 % and 22.3 % , respectively .
Finally , on the basis of the dual - band antenna , the four - band microstrip antenna is designed by adding F - shaped branches , which are 6.9 - 7.3GHz , 12.4 - 13.2 GHz , 14.3 - 14.8 GHz and 17.7 - 21.0 GHz , respectively . The gain of the antenna in each frequency band is not less than 6.0 dBi , shows good directional radiation characteristics , and the test results verify the correctness of the design . This paper presents an electric dipole antenna based on vertical structure . The antenna adopts a fan - shaped dipole and a semi - circular metal coating of a printed structure as the electric dipole and the magnetic dipole . In order to realize the broadband impedance matching of the antenna , the experimental results show that the antenna has a working bandwidth of 2.45 - 4.90 GHz , and the experimental results show that the antenna has a working bandwidth of 2.31 - 3.93 GHz and the gain is stable between 7.4 and 9.7 dBi . In this paper , three broad band printed end - beam antennas are studied . First , using the broadband operating characteristics of microstrip line to coplanar stripline balun , a printed end - beam antenna with a size of 24.24 mm 脳 30 mm is designed , which has a relative impedance bandwidth of 75 % less than 1.5 in S - band , and has a good end - beam radiation characteristic in the band .
Secondly , based on the printed monopole antenna , a broadband end - beam antenna with end - beam radiation characteristics is designed by adding directors and reflectors .
finally , by improving the structure of the director , the working bandwidth and the radiation property of the antenna are further increased without increasing the size of the antenna . This paper presents a new beam - controlled array , which is based on circular polarized helical antenna . By controlling the different rotation angles of helical antenna elements in the array , the phase difference between elements in the array can be realized . In order to verify this theory , a series of 128 circular polarized helical antenna elements are designed and processed .

【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN820

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