| 摘要 |
PURPOSE:To decrease the deterioration of an electric characteristic with respect to frequency change by constituting a branch waveguide having an electric length of pi/2 by a slit provided to the projection of a main and a sub waveguide and a square waveguide provided between the main and the sub waveguide. CONSTITUTION:Projections 3 are formed to a part of a broad face of a guide wall of the main waveguide 1 and the sub waveguide 2 (ridge waveguides). The waveguides 1, 2 are connected by a square waveguide 4 and a slit 5 is provided to the projection 3 at an interval of electric length 90 deg.. Then the branch waveguide 6 is constituted by the waveguide 4 and the slit 5. Since the electromagnetic field of the waveguides 1, 2 is concentrated onto the middle part of the waveguide 6 because of the effect of the projections 3, the electric connecting point with the waveguides 1, 2 is the tip of the projection 3. Further, the electromagnetic field is concentrated on the middle part of the slit 5 and the effect of the side walls is less and the cut-off frequency is nearly zero. Since the frequency change in the electric length of the waveguides 1, 2 and the waveguide 6 is small, the waveguide coupler is obtained, in which the frequency change in the electric characteristic is less.
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