| 摘要 |
PURPOSE:To obtain a directional-coupler type TE21 mode detector which can detect a TE21 mode with high precision, by providing coupling elements in two lines symmetrically on the axis of a cylindrical waveguide. CONSTITUTION:Coupling elements 2a and 2b are provided symmetrically on the axis of cylindrical waveguide 1 in two lines, and then coupled with sub-waveguides 3a and 3b respectively. Coupling elements are provided where the magnetic-field component in the TE21 mode is the largest. When the magnetic-field component of the TE21 mode coupling with coupling elements is denoted by A while that of the TE11 mode is by B, magnetic fields of both TE21 and TE11 modes come out of phase (A-B) in sub-waveguide 3b and come in phase in sub-waveguide 3b, so that the magnetic-field component of (A+B) will be coupled. Only the TE21 mode can be obtained at terminal 7a by applying waves propagating through sub-waveguides 3a and 3b via magic T7. Further, only the TE11 mode can be obtained at terminal 7b, so that it will be terminated by terminating set 8. |
