| 摘要 |
PURPOSE:To improve the suppressing effect of high frequency and at the same time to obtain an accurate inter-stage capacity, by using plural inductive resonators having small diameters at their tip parts and a metallic cylinder which connects these resonators. CONSTITUTION:A resonator which forms a band pass filter is made of a cylindrical dielectric material 303 having a small size of the outer circumferences close to both ends. The outer circumference of the material 303 is metallized to form an outer conductor 301, and furthermore an inner conductor 302 is added. The supressing effect of high frequency can be improved for a filter with use such a resonator. When a filter is formed with use of plural such resonators, a metallic cylinder 401 plays an important role as component element in positioning and fixing the resonator. The inner diameter of the cylinder 401 is set slightly larger than the outer diameter of the tip part of the resonator. While the outer diameter of the cylinder 401 is approximately equal to the outer diameter of the center part of the resonator. The distance between center conductors of two resonators can be controlled with high accuracy by giving an accurate control between the length of the tip part of the resonator and the length (l) of the cylinder 401. Thus the coupling capacity can be attained with good reproducibility for a band pass filter. |
