PURPOSE: To improve the omnidirectivity of radiation gain of a cross dipole antenna and to reduce the radiation of a reversely turned circularly polarized wave to the side and rear directions of the antenna.

CONSTITUTION: Two half-wavelength dipole elements respectively consisting of dipole elements 1a-1d arranged in the vertical face of an antenna supporting column 2A radiate a positively turned circularly polarized wave in a direction to the top part of the column 2A (the front of the antenna). Reflection elements consisting of conductor elements 5a-5d are arranged on the top part of the column 2A to reflect a radio wave applied to the front of the antenna to the side direction of the antenna. Aλ/4 wavelength type choke element is arranged between the elements 1a-1d and the bottom part of the column 2A to interrupt the radiation of radio waves mainly consisting of a reversely turned circularly polarized wave to the rear part of the antenna.