随着现代无线通信技术的迅速发展，第五代移动通信将多输入多输出（Multiple Input Multiple Output, MIMO）技术作为其关键技术，这表明现代无线通信系统对于天线在带宽、增益等方面提出了更高的要求。磁电偶极子天线作为一种典型的宽带、高增益、辐射方向图稳定的天线，一直受到天线领域设计者们的广泛关注，其工作带宽的进一步展宽可以大幅度提高数据的传输速率。在此背景下，本论文针对磁电偶极子天线的宽带化设计方法开展研究，主要的研究内容总结如下：

（1）蚀刻L形槽的单极化宽带磁电偶极子天线设计。在传统的单极化磁电偶极子天线的基础之上，通过在水平电偶极子贴片上蚀刻两对尺寸不同的L形槽，在低频和高频区域分别引入一个谐振点，从而大幅度地展宽了天线的工作频带。为了验证仿真结果的有效性，加工测试仿真所得的天线，通过实测数据分析可知，所设计天线的工作频段为1.36-4.15GHz，相对带宽达到了101.3%，与原始的天线相比，天线的相对带宽提升了35.4%，即从74.8%提升至101.3%，同时天线的峰值增益可以达到11.5dBi，交叉极化水平低于-20dB，且实测所得的结果与仿真结果有较好的一致性。由于所设计天线的工作频带可以覆盖2G/3G/4G以及部分Sub-6G 5G频段，如n50(1.432-1.517GHz)，n51(1.427-1.432GHz)和n78(3.300-3.800GHz)，所以该天线可以用于基站天线。

（2）加载倒L枝节的宽带双极化磁电偶极子天线设计。首先采用七边形的贴片结构代替传统的方形结构以提升天线高频处的阻抗匹配，在2.8GHz频点处产生了一个新的谐振点，天线的重合带宽从63%提升至80%；接着，通过在天线的四周加载倒L形寄生枝节的方法，进一步提升了天线低频处的阻抗匹配，在低频1.4GHz附近引入一个新的谐振点，最终所设计的双极化宽带磁电偶极子天线的重合工作频段为1.2-3.56GHz，相对带宽达到了99.2%，在整个工作频带内天线的峰值增益达到了12dBi，交叉极化水平小于-22dB，两个端口之间的隔离度大于20dB。通过对所设计天线的电流分布和输入阻抗的分析得出了天线的频带展宽原理，最终对天线做了实物加工测试，验证了天线的良好辐射性能。

（3）S频段8元阵列天线设计。S频段阵列雷达射频信号的有效发射与接收要求S频段阵列天线具有工作带宽带、高辐射效率、辐射性能稳定等特点。为了实现8元S频段阵列雷达射频信号的发射与接收功能，首先基于一阶Minkowski分形结构设计出磁电偶极子天线单元，并将平面电偶极子进行折叠以降低组阵时相邻阵元的边缘距离；然后将最优天线单元以55mm等间距均匀排布组成8元线阵，并通过在地板上蚀刻缝隙槽结构的方式进一步降低阵元间的电磁耦合。仿真和测试结果表明，所设计S频段8元阵列天线的工作带宽为25.9%（Active VSWRs≤2，2.72-3.53GHz），在整个工作频段内天线的增益稳定在16.0-17.8dBi，隔离度在20-26dB之间。

With the rapid development of modern wireless communication technology, the fifth generation consider Multiple Input Multiple Output (MIMO) as its key technology. This indicates that modern communication system put forward higher requirements for antenna in terms of bandwidth and gain. As a typical broadband, high gain and stable radiation pattern antenna, magnetoelectric dipole antenna has been widely concerned by designers in the field of antenna. The further broadening of its working bandwidth can greatly improve the data transmission rate. In this context, this thesis studies the broadband design method of magnetoelectric dipole antenna. The main research contents are summarized as follows:

(1) Design of a single-polarized broadband magnetoelectric dipole antenna with etched L-shaped slots. Based on the traditional single-polarized magnetoelectric dipole antenna, two pairs of L-shaped slots with different sizes are etched on the horizontal dipole patches, and a resonance point is introduced in the low-frequency and high-frequency regions, respectively, which greatly enhance the working frequency band of the antenna. To validate the effectiveness of the simulation results, the antenna is fabricated and measured. The measured data analysis confirms that the designed antenna operates in the frequency range of 1.36 to 4.15GHz, achieving a relative bandwidth of 101.3%. Compared to the original antenna, the relative bandwidth of the antenna has increased by 35.4%, from 74.8% to 103.1%. Additionally, the maximum gain of the antenna can up to 11.5dBi, with a cross-polarization level below -20dB. The measured results show good consistency with the simulation results. Due to the wide frequency coverage of the antenna, including 2G/3G/4G and some sub-6G 5G bands such as n50 (1.432 to 1.517GHz), n51 (1.427 to 1.432GHz), and n78 (3.300GHz to 3.800GHz), the antenna can be a good candidate for base station applications.

(2) A dual-polarized broadband magnetoelectric dipole antenna loaded with inverted L-shaped branches is presented. a heptagonal patch structure is applied instead of the traditional square structure to improve the impedance matching at high frequencies. A new resonance point is introduced at 2.8GHz, and the overlapped bandwidth of the antenna is increased from 63% to 80%. Then, by loading inverted L-shaped parasitic branches around the antenna, the impedance matching of the antenna at low frequency is further improved, and a new resonance point is introduced near 1.4GHz at low frequency. Finally, the overlap working frequency band of the proposed antenna is 1.2-3.56 GHz, the relative bandwidth reaches 99.2 %, and the available peak gain can be as high as 12dBi. Meanwhile, its cross‐polarization level (CRPL) is lower than −22dB, and the isolation between the two ports is larger than 20 dB across the operating frequency. The principle of bandwidth enhancement for the antenna is derived through analysis of the current distribution and input impedance. The antenna is fabricated and measured to validate its excellent radiation performance.

(3) Design of S-band 8-element array antenna. The effective transmission and reception of S-band array radar RF signals require that the S-band array antenna has the characteristics of broadband working band, high radiation efficiency and stable radiation performance. In order to transmit and receive the radio frequency signal of the 8-element S-band array radar, Firstly, the magnetoelectric dipole antenna unit is designed based on the first-order Minkowski fractal structure, and the planar electric dipole is folded to reduce the edge distance of adjacent array elements. Then, the optimal antenna elements are evenly arranged with 55mm equal spacing to form an 8-element linear array, and the electromagnetic coupling between the array elements is further reduced by etching the slot structure on the floor. According to the simulation and measurement results, the S-band 8-element array antenna has a working bandwidth of 25.9% (Active VSWRs≤2, 2.72-3.53GHz). The antenna maintains a stable gain of 16.0dBi to 17.8dBi across the entire operating frequency range, and the isolation between elements is between 20dB and 26dB.

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