| 摘要 |
PROBLEM TO BE SOLVED: To provide a feed used in common for two frequencies with a simple structure and a small size that can easily be manufactured. SOLUTION: A primary radiator 100 is provided with a 1st waveguide 1 of a cylindrical shape, a step converter 4, a 2nd waveguide 2, an electromagnetic horn section 3, and a reflection section 16. The inner diameter of the 1st waveguide 1 is smaller than the inner diameter of the 2nd waveguide 2. The inner diameter of the step converter 4 is larger than the inner diameter of the 1st waveguide 1 and smaller than the inner diameter of the 2nd waveguide 2. A 1st probe 11 to which a signal in a high frequency band (wavelengthλ1) is fed is provided in the 1st waveguide 1 at a distance ofλ1/4 from the reflecting plate 16. A 2nd probe 12 to which a signal in a low frequency band (wavelengthλ2) is fed is provided in the 2nd waveguide 2 at a distance ofλ2/4 from the step converter 4. The characteristic impedance of the step converter 4 can be obtained from the characteristic impedance of the 1st waveguide 1 and the 2nd waveguide 2.
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