CIRCULARLY POLARIZED ANTENNA AND RADAR DEVICE USING IT

摘要

A circularly polarized antenna comprises a dielectric substrate, a base conductor joined to one side of the dielectric substrate, a circularly polarized antenna element formed on the opposite side of the dielectric substrate, metal posts one end of each of which is connected to the base conductor and extends through the dielectric substrate in the direction of the thickness, the other end of each of which extends to the opposite side of the dialectic substrate, and which are so arranged at predetermined intervals as to surround the antenna elements and define a cavity, and a frame conductor provided on the opposite side of the dielectric substrate, short-circuiting the other ends of the metal posts in the arrangement direction, and extending by a predetermined distance in the antenna element direction. In the circularly polarized antenna, no surface wave is produced thanks to the cavity and frame conductor to realize desired antenna radiation characteristics. The circularly polarized antenna has a frequency characteristic of the antenna gain which has a sharp notch in the RR radio wave radiation inhibition range by using the cavity resonance phenomenon. Therefore, radio wave interference with EESS and radio astronomy operation is effectively reduced.