| 摘要 |
PROBLEM TO BE SOLVED: To provide a waveguide branching filter capable of being applied to a multi-frequency shared circuit and obtaining sufficient inter-frequency isolation even in the case that plural frequency bands are adjacent. SOLUTION: This waveguide branching filter is composed of a main waveguide, a sub-waveguide 2 and plural branching waveguides 4 for constituting a hybrid coupler 3, and by providing a bent waveguide 5 as a phase correction means in the sub-waveguide 2 so as to turn a phase difference inside the sub- waveguide and inside the main waveguide to the integral multiple of 2πfor a frequency to be coupled to the sub-waveguide 2, the frequency to be coupled to a coupling port is synthesized in the same phase and coupled without degrading characteristics. In the meantime, since the frequency band not to be coupled to the coupling port causes phase shift, a coupling amount to the coupling port is small and high isolation is obtained. Also, since the plural frequency bands are transmitted to a common port, it is applied to the multi-frequency shared circuit.
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