天线作为无线设备的前端，在通信系统中具有举足轻重的位置，其性能的好坏关乎通信系统的有效性和可靠性，随着无线技术的高速发展，无线通信系统对高性能天线的需求越来越迫切。磁电偶极子天线因能实现较宽的工作带宽，且具有高增益，低交叉极化水平和稳定的辐射方向图等优异特性而受到广泛研究。基于此，本文对磁电偶极子天线的宽带化设计方法展开研究，具体研究内容如下：

    （1）紧凑型宽带磁电偶极子天线设计。以传统磁电偶极子天线为基础，设计了一款加载类Minkowski分形结构的磁电偶极子天线。在天线整体尺寸不变的前提下，通过加载二阶类Minkowski分形结构，延长了贴片上的电流路径，降低了天线的中心频率，从而展宽天线带宽并缩减天线尺寸。对该天线模型进行加工及测试，由实测结果得出：所提出的天线工作在1.58-2.81GHz频段，实现了56%的相对带宽，与分形前的天线相比，相对带宽提升了19%。同时，天线的电尺寸从0.24λ₁×0.616λ₁×0.48λ₁减小到0.218λ₀×0.56λ₀×0.438λ₀，实现了24.6%的体积缩减。在工作频段内，最大增益可达10.1dBi，E面和H面的辐射图基本相同，前后比大于14dB，且实测结果与仿真结果具有较好的一致性。该天线可应用于多种无线通信系统。

    （2）加载圆环结构的宽带磁电偶极子天线设计。首先设计了一款四贴片的磁电偶极子天线，该天线共有两个谐振点，分别在2.3GHz和3GHz。通过在平面电偶极子贴片上加载一对金属圆环，改善了天线在低频处的阻抗匹配特性，在约1.6GHz处增加了一个谐振点，天线的工作频带由1.98-3.24GHz提升到1.5-3.26GHz（|S₁₁|≤-10dB），有效展宽了天线的工作带宽，经过仿真可得，天线在工作频带内共有三个谐振点，实现了74%的相对带宽，平均增益为8.5dBi且波动较小，其前后比大于19dB，交叉极化水平均小于-30dB。特别地，为了进一步增大天线带宽，对上述天线做了进一步改进，在所加载金属圆环的内部引入了小金属圆环，并在两金属圆环相交处开有缝隙。小金属圆环的加载有效的改善了天线高频段的阻抗匹配，在约3.6GHz处产生了一个新的谐振频点。并对天线的阻抗特性和表面电流做了详细分析。得出，当环路长度接近半个波长时，环路会产生新的谐振模式，从而增加阻抗带宽。通过这种方式，天线的阻抗带宽从48.3%（1.98-3.24GHz）提升到86.8%（1.465-3.71GHz），即带宽提升了79.7%。在工作频段内，天线的增益为7.42-12.8dBi，且获得了良好的辐射特性。

    As the front end of wireless devices, antennas play a pivotal role in communication systems. Its performance is about the validity and reliability of communication system. With the rapid development of wireless technology, the demand for high-performance antennas in wireless systems is becoming more and more urgent. Magnetoelectric dipole antennas have been widely studied for their excellent characteristics such as wide frequency band, high gain, low cross-polarization level and stable radiation pattern. Based on this, the broadband design method of magnetoelectric dipole antenna is studied in this paper. The specific research content is as follows:

    (1) Design of compact broadband magnetoelectric dipole antenna. Based on the traditional magnetoelectric dipole antenna, a magnetoelectric dipole antenna loaded with Minkowski-like fractal structure was designed. Under the premise that the overall size of the antenna remains unchanged. By loading the second-order Minkowski fractal structure, the current path on the patch is extended and the center frequency of the antenna is reduced, thereby broadening the antenna band and realizing the antenna miniaturization. The antenna is processed and tested. According to the measured results: the proposed antenna works in the 1.58-2.81GHz frequency band and achieves 56% relative bandwidth, which is 19% higher than that of the pre-fractal antenna. Meanwhile, the electrical size of the antenna is reduced from 0.24λ₁×0.616λ₁×0.48λ₁ to 0.218λ₀×0.56λ₀×0.438λ₀, and the size is reduced by 24.6%. In the operating frequency band, the radiation patterns of the E plane and the H plane are basically the same, the front-to-back ratio (FBR) is greater than 14dB. The maximum gain can reach 10.1dBi. There is good agreement between the measured and simulated results. The antenna can be applied to a variety of wireless communication systems.

    (2) Design of broadband magnetoelectric dipole antenna loaded with loops structure. First, a four-patch magnetoelectric dipole antenna was designed, which has two resonant points at 2.3GHz and 3GHz respectively. By loading a pair of metal loops on a planar electric dipole patch, impedance matching at low frequencies is improved. A resonance point is added at about 1.6GHz in low frequency region. The operating frequency band of the antenna has been improved from 1.98-3.24GHz to 1.5-3.26GHz (|S₁₁|≤-10dB). The operating bandwidth of the antenna is effectively broadened. After simulation, it can be found that there are three resonance points in the operating band of the antenna. 74% relative bandwidth was obtained. The average gain was 8.5dBi with little fluctuations. The FBR is greater than 19dB and cross-polarization levels is less than -30dB. In particular, the above antenna has been further improved to further extend the band width. A small metal ring is introduced inside the loaded metal loops, and a gap is opened at the intersection of the two metal loops. The loading of the small metal loop effectively improves impedance matching in the high frequency region, creating a new resonant frequency point at about 3.6GHz. The impedance characteristics and surface current of the proposed antenna are analyzed in detail. It shows that when the loops length approaches half a wavelength, the loops contribute new resonant modes, thereby increasing the impedance bandwidth. In this way, the antenna impedance bandwidth in terms of 10dB is improved from 48.3% (from 1.98 to 3.24GHz) to 86.8% (from 1.465 to 3.71GHz), i.e., 79.7% bandwidth enhancement is achieved. The antenna gain ranges from 7.42dBi to 12.8dBi across the operational frequency region. Good radiation characteristics are obtained.

[1]习磊.高性能MIMO天线及阵列技术研究[D].陕西:西安电子科技大学,2019.

[2]何业军,黄伟,陈亚玲等.支持未来全频谱接入通信的基站天线研究综述[J].电波科学学报,2023,38(01):15-26+43.

[3]Kwai-Man Luk and Biqun Wu. The Magnetoelectric Dipole-A Wideband Antenna for Base Stations in Mobile Communications[J]. Proceedings of the IEEE, 2012, 100(7):2297-2307.

[4]Deschamps,G.A. Microstrip Microwave Antennas[C].3rd USAF Symposium on Antennas,1953.

[5]Howell J. Microstrip Antennas[J]. IEEE Transactions on Antennas and Propagation,1975,23(1):90-93.

[6]Munson R. Conformal Microstrip Antennas and Microstrip Phased Arrays[J]. IEEE Transactions on Antennas and Propagation,1974,22(1):74-78.

[7]Pozar DM. Microstrip Antenna Aperture Coupled to a Microstripline[J]. Electronics Letters,1985.

[8]曾现祥,陈永照，黄波.一种耦合馈电的毫米波双频微带天线[J].通信技术,2019,52(10)：2549-2554．

[9]金秀梅,叶顺涛,李运志,赵继鹏,吴志峰. C 波段宽带双极化微带贴片天线设计[J].无线电工程,2020,50(09):792-796.

[10]谭祥俊,卢忠亮,宋谦,彭强.基于特征模式分析的宽带圆极化超表面天线[J].电子元件与材料,2022, 41(07):745-750.

[11]Zhang-Fa Liu, Pang-Shyan Kooi, Le-Wei Li, Mook-Seng Leong and Tat-Soon Yeo. A Method for Designing Broad-band Microstrip Antennas in Multilayered Planar Structures[J]. IEEE Transactions on Antennas and Propagation, 1999, 47(9):1416-1420.

[12]Ahmad Firdausi and Mudrik Alaydrus. Designing Multiband Multilayered Microstrip Antenna for mmWave Applications[C]. 2016 International Conference on Radar, Antenna, Microwave, Electronics, and Telecommunications (ICRAMET), Jakarta, Indonesia, 2016:99-102.

[13]Y. Wang, X. Zhang, S. Liu. A Multilayer Microstrip Printed UWB LPDA[C].2021 International Applied Computational Electromagnetics Society (ACES-China) Symposium, Chengdu, China, 2021:1-2.

[14]Kwok Kan So, Kwai Man Luk and Chi Hou Chan. A High-Gain Circularly Polarized U-Slot Patch Antenna Array[J]. IEEE Antennas and Propagation Magazine,2018, 60(5):147-153.

[15]Diptiranjan Samantaray and Somak Bhattacharyya. A Gain-Enhanced Slotted Patch Antenna Using Metasurface as Superstrate Configuration[J]. IEEE Transactions on Antennas and Propagation, 2020, 68(9):6548-6556.

[16]Deepak K Naik, Amit K. Sahu, Rajeev K. Parida, P Raiguru, Dhruba C. Panda, Rabindra K. Mishra. Design of a broadband U-slot loaded E-shaped patch antenna using characteristic mode analysis[J]. AEU-International Journal of Electronics and Communications,2022,154(154310):1434-8411.

[17]唐震,汪立新,汤天宇.类Minkowski分形天线的分析与设计[J].电子技术应用,2019,45(07):77-80.

[18]Hau-Wah Lai and Kwai-Man Luk. Design and Study of Wide-band Patch Antenna Fed by Meandering Probe[J]. IEEE Transactions on Antennas and Propagation, 2006, 54(2):564-571.

[19]Hong Hyun Bae, Tae Hwan Jang, Hong Yi Kim and Chul Soon. Park. Broadband 120 GHz L-Probe Differential Feed Dual-Polarized Patch Antenna with Soft Surface[J]. IEEE Transactions on Antennas and Propagation, 2021, 69 (10):6185-6195.

[20]Chlavin A. A New Antenna Feed Having Equal E-and H-Plane Pattems[J]. Antennas&Propagation Transactions of the Ire Professional Group on,1954,2(3):113-119.

[21]Kwai-Man Luk, Hang Wong. A New Wideband Unidirectional Antenna Element[J]. International Journal of Microwave Optical Technology, 2006,1(1):35–44.

[22]Lei Ge, Kwai Man Luk. A Wideband Magneto-electric Dipole Antenna[J]. IEEE Transactions on Antennas and Propagation, 2012,60(11): 4987-4991.

[23]Quanping Li, Hua Zhu, Xiuping Li, Qingwen Li. A Compact Broad E-plane Beamwidth Magneto-electric Dipole Antenna Array for UWB Application[J]. Electromagnetics,2019,39(2):80-88.

[24]吴思雨,赵建平,徐娟等.低剖宽带磁电偶极子天线的设计[J].通信技术,2020,53(08):1873-1876.

[25]Hao Cheng, Bo Yuan, Xiaohong Zhang, et al. Wideband E-shaped Magneto-electric Dipole Antenna[C]. 2016 IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT), 2016, (2): 638-640.

[26]张泽胜.紧凑型宽带磁电偶极子天线的研究[D].杭州:杭州电子科技大学,2019.

[27]陈茂洋,肖祺.一种 M 型超宽带磁电偶极子天线设计[J].通信技术,2020,53(05):1285-1289.

[28]Jingtao Zeng and Kwai-Man Luk. A Simple Wideband Magnetoelectric Dipole Antenna with a Defected Ground Structure[J]. IEEE Antennas and Wireless Propagation Letters, 2018, 17(8):1497-1500.

[29]Mingjian Li, Kwai-Man Luk. A differential-fed magneto-electric dipole antenna for UWB applications[J]. IEEE Transactions on Antennas and Propagation ,2013,6(1): 92-99.

[30]Zilong Ma, Chihou Chan. Waveguide-based Differentially-fed Dual-polarized Magneto-electric Dipole Antennas[J]. IEEE Transactions on Antennas and Propagation ,2017,65(8):3849-3857.

[31]Chenyang Shuai and Guangming Wang. A Simple Ultra-wideband Magneto-electric Dipole Antenna with High Gain[J]. Frequenz, 2018,72(1-2):27-32.

[32]Hau Wah Lai, Kwok Kan So, Hang Wong, Chihou Chan, Kwai Man Luk. Magnetoelectric Dipole Antennas with Dual Open-ended Slot Excitation[J]. IEEE Transactions on Antennas and Propagation ,2016,64(8):3338-3346.

[33]Xuewu Cui, Feng Yang, Min Gao, Longjian Zhou, Zhipeng Liang and Fei Yan. A Wideband Magnetoelectric Dipole Antenna with Microstrip Line Aperture-Coupled Excitation[J]. IEEE Transactions on Antennas and Propagation, 2017, 65(12):7350-7354.

[34]杨浩楠,曹祥玉,高军,杨欢欢,李桐,高坤.一款基于容性加载结构的宽带磁电偶极子天线[J].空军工程大学学报(自然科学版),2020,21(05):89-93.

[35]Wenbo Liu, Tao Wang, Darong Gao, Yong Liu and Xingli Zhang. Low-Profile Broadband Magnetoelectric Dipole Antenna with Dual-Complementary Source[J]. IEEE Antennas and Wireless Propagation Letters, 2020, 19(12):2447-2451.

[36]Aditya Singh and Carlos E. Saavedra. Low-Profile CPW-PS Fed Magneto-Electric Antenna[J]. IEEE Antennas and Wireless Propagation Letters, 2021, 20(12):2471-2475.

[37]Jingxue Wang, Yujing Li, Fan Wu, Defu Jiang, Junhong Wang. Millimeter-wave Wideband Endfire Magnetoelectric Dipole Antenna Fed by Substrate Integrated Coaxial Line[J]. IEEE Transactions on Antennas and Propagation, 2022,70(3):2301-2306.

[38]张呈辉,曹祥玉,高军,李思佳.宽频带宽波束磁电偶极子天线设计[J].电子与信息学报,2015,37(03):758-762.

[39]Guangwei Yang, Jianying Li, Jiangjun Yang and SG Zhou. A Wide Beamwidth and Wideband Magnetoelectric Dipole Antenna[J]. IEEE Transactions on Antennas and Propagation,2018,66(12): 6724-6733.

[40]Xuan Zhang, Yong-Chang Jiao, Zi-Bin Weng, Yi-Xuan Zhang and Shu Feng. Wideband Magneto-electric Dipole Antenna with a Claw Shaped Reflector for 5G Communication Systems[J]. Microwave and Optical Technology Letters, 2019, 61(9):2098-2104.

[41]Suidao Fu, Zhenxin Cao, Xin Quan, Changzhi Xu. A Broadband Dual-polarized Notched-band Antenna for 2/3/4/5G Base Station[J]. IEEE Antennas and Wireless Propagation Letters,2020,19(1):69-73.

[42]Yunxia Feng, Fushun Zhang, Guojun Xie, Yunjie Guan, Jifeng Tian. A Broadband and Wide-beamwidth Dual-polarized Orthogonal Dipole Antenna for 4G/5G Communication[J]. IEEE Antennas and Wireless Propagation Letters, 2021, 20(7): 1165-1169.

[43]隋涛,邢斯瑞,孙伟,安向东.星载L波段宽带高增益圆极化微带天线设计[J].电子技术应用,2022,48(01):138-141+151.

[44]朱熙铖,陶正壮,肖凌峰.一种宽带圆极化环形天线[J].电子元件与材料,2022,41(11):1215-1221.

[45]张馨心,姚爱琴,柴晋强. CPW馈电的超宽带天线设计[J].压电与声光,2019,41(06):894-896+909.

[46]Jiexi Yin, Qi Wu, Chen Yu, Haiming Wang and Wei Hong. Broadband Endfire Magnetoelectric Dipole Antenna Array Using SICL Feeding Network for 5G Millimeter-Wave Applications[J]. IEEE Transactions on Antennas and Propagation, 2019,67(7):4895-4900.

[47]梁青,王超,苏正东,熊伟.蝶形六陷波超宽带天线设计与研究[J].传感器与微系统,2021,40(04):23-25.

[48]廖银霜,王代强.一种五陷波超宽带天线的设计[J].电讯技术,2021,61(05):640-645.

[49]Weiheng Chen, Zhiqiang Yu, Jingfeng Zhai, Jianyi Zhou. Developing Wideband Dual-circularly Polarized Antenna with Simple Feeds Using Magnetoelectric Dipoles[J]. IEEE Antennas and Wireless Propagation Letters,2020, 19(6):1037-1041.

[50]Botao Feng, Liangying Li, KwokL. Chung, Yansheng Li. Wideband Widebeam Dual Circularly Polarized Magnetoelectric Dipole Antenna/array with Meta-columns Loading for 5G and Beyond[J]. IEEE Transactions on Antennas and Propagation, 2021, 69(1):219-228.