| 摘要 |
PURPOSE:To improve the selection properties by providing plural ring-shaped resonators which are set adjacent to each other with close connections together with other ring-shaped resonators having rough connections to said other types of resonators and having no connections between ring-shaped resonators other than said ones and an input/output circuit. CONSTITUTION:The greater part of the energy components of signals coincident with resonance frequencies of resonators 5-7 respectively is connected to a resonator 6 from the resonator 5 with a connection degree C1 and then to an end of an input/ output circuit 2. While the rest of the energy components of those signals is connected to the resonator 7 from the resonator 5 with a connection degree C2 and then to the resonator 6 from the resonator 7 with a connection degree C2. The traveling direction of the energy connected to the resonator 6 from the resonator 5 is set opposite to the traveling direction of the energy connected to the resonator 6 from the resonator 5 via the connector 7 at the inside of the resonator 6 owing to the difference of connection frequencies between both types of energy. These energies are partially eliminated to each other when they are delivered to an end of the circuit 2 from the resonator 6. Thus it is possible to obtain a BPF having a pole with sharp selection properties. |
