| 摘要 |
PROBLEM TO BE SOLVED: To provide a primary radiator for a parabolic antenna which can be downsized without deteriorating the cross polarization wave characteristic and whose cost can be reduced. SOLUTION: A circuit board 22 is placed at a distance of nearlyλg/4 from a short-circuit end face of a circular waveguide 20, and a 1st probe 23 and a 2nd probe 24 are formed by a strip line on one side of the circuit board 22. e.g. at a side thereof opposite to the short circuit end face of the circular waveguide 20. The 1st probe 23 is placed vertically toward a waveguide center axis and the 2nd probe 24 is placed horizontally toward the waveguide center axis. A stub 25 is placed to the circular waveguide 20 at a distance of about 0 toλg/4 from the circuit board 22 in its front direction at an angular distance of 135 deg. from the 1st probe 23 and the 2nd probe 24, respectively. The stub 25 acts like suppressing the deterioration in the cross polarization wave characteristic due to disturbance in an electromagnetic field in the circular waveguide 20 caused when the 1st probe 23 and the 2nd probe 24 are placed on the same plane.
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