| 摘要 |
PROBLEM TO BE SOLVED: To provide a small and inexpensive primary radiator which is applied to a reflector having a noncircular reflecting surface shape, while securely preventing deterioration in cross-polarization characteristics. SOLUTION: A dielectric feeder 11 has a hold part 11a, which is inserted into a waveguide 10 and a trumpet-shaped radiation part 11b, which is different in radiation angle between the major-axis direction and short-axis direction and has plural annular grooves 15 formed in an end surface of its radiation part 11b to a depth about 1/4 times the wavelengthλ0 of the radio wave. A couple of flat surfaces 14 are formed, by cutting the outer peripheral surface of the hold part 11a at opposite positions along an axis and arranged along the long axis of the radiation part 11b, so that the primary radiator functions as a phase compensation part which compensates the propagation phase difference that the radiation 11b has. Furthermore, a stepped hole 13 is formed by connecting two recessed grooves 13a and 13b inwardly from the end surface of the hold part 11a and the depth of both the recessed grooves 13a and 13b is set to almost 1/4 times the wavelengthλεof a radio wave, so that the radiator functions as an impedance conversion part.
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