In recent years, a multiband antenna that enables communication over a plurality of frequency bands for ensuring communication capacity has been put to practical use, for example, as a base station for mobile communication and an antenna device for Wi-Fi (registered trademark) communication equipment.
A multiband antenna is disclosed as a multiband antenna array in, for example, FIGS. 11, 12, and 13 of PTL 1. This antenna array includes an antenna reflector, and an array of high-band and low-band crossed-dipole antenna elements alternately aligned on the antenna reflector. Further, central conductive fences 1340 are provided between the alignments to reduce mutual coupling. In addition, in PTL 2, in FIGS. 2a, 2b, and 2c, a decoupling element (decoupling structural element 17) is arranged between individual antenna elements (radiation element module 1) of a single-frequency antenna array.