| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact directional coupler reducing a coupling deviation within a use frequency band.SOLUTION: A directional coupler includes a first output port 12 of a first coupling line 10 connected to a second input port 21 of a second coupling line 20, and a first isolation port 14 of the first coupling line 10 connected to a second coupling port 23 of the second coupling line 20. The directional coupler further includes an open stub 30 disposed between the first isolation port 14 and the second coupling port 23, with an electric length of 1/2 wavelength of the center frequency of the use frequency band. Also, the total electric length of the first coupling line 10 and the second coupling line 20 is set shorter than 1/4 wavelength of the center frequency of the use frequency band. |
