To form a vertical antenna array by arranging truncated conical conductor disks oppositely above and under the dipole antenna element with it as a center and to obtain high gain without making an antenna diameter large by making the directivity of a vertical plane sharp.
Truncated conical conductor disks 2a and 2b are arranged oppositely above and under the dipole antenna element 1 with it as a center. The conductor disks 2a and 2b are supported by spacers 5 for fixing. In the dipole antenna element 1, an internal conductor 3b is extended as long as 1/4 wavelength of a use frequency band and is exposed in an upper end part of a coaxial feedline 3 and a sleeve conductor 4 whose length is 1/4 wavelength is also connected to an external conductor downward. For the spacers 5 for fixing, insulating material of a low dielectric constant is used not so as to affect directivity. Also, the interval between the two conductor disks 2a and 2b is defined as about 1/2 wavelength so as to prevent a higher mode from generating.
ISHIZAKI TOSHIO
OGAWA KOICHI
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