Abstract: In this array antenna, if (a) a pair of antennas (130) are used and transmission signals having the same phase are fed in parallel via two secondary cables (33) branching off of a main cable (32), letting Z represent the impedance of the main cable (32), the impedance of each secondary cable (33) and the input impedance of each antenna (130) is set to 2Z; if (b) a set of three antennas (130) is used, the impedance of each secondary cable (33) and the input impedance of each antenna (130) is set to 3Z; and if (c) a set of N antennas (130) is used, the impedance of each secondary cable (33) and the input impedance of each antenna (130) is set to N×Z. In each case, the impedances match over a wide frequency band.

Abstract: A vertically polarized antenna having a wide relative bandwidth while having a thin structure against vertically polarized waves. The vertically polarized antenna includes: a ground plate, a conductor plate, two or more feeding conductors, and short-circuit conductors grouped with the feeding conductors, respectively. The conductor plate is arranged parallel to the ground plate such that the whole of the conductor plate is overlapped with the ground plate when seen from a direction of a normal line of the ground plate; each of the feeding conductors connects the ground plate and the conductor plate at a position different from a center of the conductor plate; and each of the short-circuit conductors connects the ground plate and the conductor plate near the feeding conductor grouped with the short-circuit conductor.