| 摘要 |
<p>A small ladder-type electric filter for use in radio equipment or the like, includes a casing (1), a plurality of resonators (x) having a small mechanical quality coefficient and a frequency constant, and a plurality of resonators (4) having a large mechanical quality coefficient. The small mechanical quality coefficient resonators and the large mechanical quality coefficient resonators being combined in series-parallel to each other. The external size of the large mechanical quality coefficient resonators is substantially equal to the external size of the small mechanical quality coefficient resonators. A plurality of terminal plates (6,9,12,13) hold the plurality of small and large mechanical quality coefficient resonators in the casing. Slits (5) are selectively formed in side edges of each of the plurality of large mechanical quality coefficient resonators for adjusting the resonance frequency of the large mechanical quality coefficient resonators to a predetermined resonance frequency. Therefore, the size of the casing can be determined in accordance with the frequency constant of the small mechanical quality coefficient resonators. <IMAGE></p> |
