PURPOSE: To correct the disturbance of a directional pattern of horizontal plane radiation electric field by changing the disposition at least one of groups of parasitic earth type reflecting antennas or controlling the distance between the base of the antenna and the earth surface.

CONSTITUTION: As shown in a figure (a), four parasitic earth type reflecting antennas 5 shown by A, B, D and E are provided around a main antenna 3, i.e., on a circumferential line 4. The antenna C is set inside the line 4 with a shift given intentionally to the left side of a center line X of directivity. Thus a directional pattern 6A shown in the figure (a) is obtained from such disposition of the antenna 3 and the antenna group 5. When the asymmetrical properties DI and DII of the directional pattern are corrected, the distance between the base of the reflecting antenna 5 of D or E of a figure (b) and the earth surface is finely adjusted. Thus it is possible to obtain a directional pattern 6B free from disturbance as shown in the figure (b).