| 摘要 |
PURPOSE:To improve the cutoff properties of the high frequency side of a band pass filter, by separating the two parallel resonators from each other in terms of the electric field by means of a masking plate and at the same time forming a trap circuit by the capacity between the parallel resonators and a shielding case. CONSTITUTION:The 1/4 resonators 11 and 11' are formed to a bobbin having plural flanges. One end of this resonator is opened with the other end connected to an earth terminal. On the other hand, a shielding case 13 has a coupling window 14 plus masking plates 15 and 16 to form 4 chambers of 17 and 18. The resonators 11 and 11', an input winding 19 and an output coils 20 and 20' are provided in the center chambers 18 respectively. And end of the coils 20 and 20' each is connected to capacitors 21 and 21' respectively to form the parallel resonators. Furthermore auxiliary windings 22 and 22' are provided in the chambers 18 to be induced and connected to the coils 20 and 20'. An end of each of the windings 22 and 22' is connected to the earth terminal with the other end connected to the other end of each of the capacitors 20 and 20'. The windings 22 and 22' are also connected to each other. |
