| 摘要 |
PURPOSE:To facilitate the matching even when a wide band characteristic is required for a radio wave in a low frequency band, by providing coupling holes of plural stages with positions and sizes which ensure the satisfactory matching for each frequency band, and providing a BPF and a matching part to a demultiplex feed circuit in response to the coupling holes and with each frequency band connected from the coupling hole. CONSTITUTION:Coupling holes (b) and (b') for frequency band fl are set toward the horn opening, and a BPF11 for direct coupling frequency band fl is connected to the output terminal of the holes (b) and (b') respectively. While coupling holes (a) and (a') for frequency band fm are set toward the horn input terminal, and a BPF12 for direct coupling frequency band fm is connected to the output terminal of the holes (a) and (a') respectively. An impedance transformer 13 performs matching with the BPF11 and BPF12 for the frequency bands f and fm respectively. A synthetic matching circuit is formed with these filters 11 and 13 and the transformer 13. |
