| 摘要 |
PURPOSE:To make steep the leading characteristics without increasing the number of stages of band pass filters, by polarizing the attenuation region through the provision of coupling hole at the capacitive coupling section of an inter digital type band pass filter in which the attenuation region is of nonpolar type. CONSTITUTION:An input transformer T0 and output transformer Tn+1, or resonant elements 11-13 and 14-16 in a row are located by inserting a partition plate 17 in a shield case 19. Other than the main coupling circuit among the resonant elements 11 and 12, 12 and 13, 13 and 14, 14 and 15, and 15 and 16, a subcoupling circuit is constituted between the resonant elements 11 and 16 via a circular coupling hole 18. In this case, since the current flowing to the resonant element 11 is reverse to the direction of the current flowing to the resonance element 16, the resonance element 11 and 16 are of capacitive couling to polarize the attenuation region. |
