Review of base station antennas for future all-spectrum-access communications（Invited）

With the rapid update of mobile communication system, more and more frequency bands are employed, so the all-spectrum-access communications become the development trend of base station antenna in the future. However, the ever-decreasing site resources require more miniaturized base station antenna. First, this paper introduces the current research advances and achievements on multi-band base station antenna, summarizes four types of multi-band structures: side-by-side, interleaved, stacked and embedded schemes, and focuses on analyzing the principle and suppression method of cross-band coupling. Then, it is concluded that share-aperture structure and cross-band decoupling technologies are the key for future all-spectrum base station antenna. Finally, the limitations of the current share-aperture schemes and cross-band decoupling technologies are expounded. And the future research directions of full-spectrum-access base station antennas are prospected, including the combination technologies of various share-aperture structures, broadband cross-band decoupling and the decoupling methods for massive share-aperture antenna array.