Contents I. Introduction
With the development of 5G mobile communication technology, the research on mmWave is flaring like fire due to the wider spectrum resources of mmWave. At the same time, different countries and regions have specific divisions for 5G millimeter waves. For example, the millimeter-wave frequency bands planned by China are mainly in the range of 24.25-27.5 GHz and 37-42.5 GHz, while the millimeter-wave frequency bands planned by the EU are mainly in the range of 24.2527.5 GHz, 31.8-33.4 GHz and 40.5-43.5 GHz. Therefore, it is of great significance and value to make the antenna to operate in multiple frequency bands. In [1], the third-order resonance structure is formed by the hairpin resonator, the U-shaped groove in the middle, and the patch on the top layer, the bandwidth is extended to a certain extent, but the spectral range is limited. Although a wide-bandwidth magnetoelectric dipole structure antenna with a defect ground structure was proposed [2], its structure is complex and the processing cost is high. In [3], a differentially driven aperture antenna was used, where the antenna has high gain and wide bandwidth, however its aperture is large and the overhead is too high. Lou et al. [4] illustrates the use of massive MIMO arrays, however the arrays still cannot meet the needs of broadband and low cost.
