| 摘要 |
PURPOSE:To reduce the types of band pass filters and to obtain an inexpensive coupler in which the matching between the line and the device is easy, by providing the 1st and the 2nd three-winding transformers where the 1st and the 2nd windings are mutually connected, and a balanced network connected between the 1st winding end of the 2nd three-winding transformer and ground. CONSTITUTION:The ternary winding terminal 104 of the three-winding transformer 7 is connected to a connecting point 109 between the 1st winding and the 2nd winding of the 2nd three-winding transformer 8. The other ends 105, 107 of the ternary winding of the transformers 7, 8 are both grounded. The 2nd winding terminal 108 of the 2nd transformer 8 is connected to the balanced network (BN) 9 and the other end of the network 9 is grounded. The 1st winding terminal 110 of the transformer 8 is connected to the input of a reception band filter 5. The said transmission and reception band filter 10 is a band pass filter passing through both transmission and reception signals FS and FR. Thus, the filter is of the same constitution as the transmission and reception band pass filter used for the line coupler installed at a remote station. That is, the types of the band pass filters are decreased. |
