The signal feeding may induce a feed current flowing in one direction on the radiation plate 50. However, the feed current will have a non-symmetrical distribution on the radiation plate 50 because, in the comparative example, the power supply is unidirectional on the exemplary feeding board 1000. The asymmetry of the feed current causes asymmetry of the electromagnetic wave radiated from the radiation plate 50, which can be an inhibitory factor of antenna quality.

FIG. 9 shows the asymmetry of the radiation pattern according to the comparative example. In the structure according to the comparative example, the center line CL1 of the radiation pattern makes a movement (d) to asymmetry from the reference line L0 in the same polarization and is asymmetric.

As shown in FIG. 8, the feeding method according to at least one embodiment of the present disclosure can have a feeding method for radiating a single polarized wave through at least two points of the radiation plate 50, a so-called dual feeding method.

A positive feed current and a negative feed current can be formed in opposite directions by the first reference-phase coupling electrode 323 and the first antiphase coupling electrode 325. In addition, the reverse negative feed current formed in the first antiphase coupling electrode 325 may be interpreted as an electrically positive feed current. Therefore, it can be seen that the first reference-phase coupling electrode 323 and the first antiphase coupling electrode 325 form a feed current in the same direction, which enables the radiation plate 50 to function as a dipole antenna having symmetry.