| 摘要 |
<p>940,838. Band-pass filters. STANDARD TELEPHONES & CABLES Ltd. Sept. 25, 1959 [Sept. 30, 1958], No. 32657/59. Heading H1W. Tunable band-pass filter includes two tunable tank circuits separated by a conductive partition wall 10, having respective inductive lines 1, 2 extending parallel to the wall and respective variable capacitors 3, 4 to tune the respective lines, and includes a coupling loop 8 which extends through a coupling slot 9 in the wall 10, the coupling loop having each end attached to an inner face of a respective tank circuit, end portions extending substantially parallel to the lines 1, 2 and a middle portion extending in a saddle-shaped manner through the coupling slot, the slot and the loop being so dimensioned that their frequency characteristics of magnetic coupling are compensative to provide either a constant coupling factor or a constant bandwidth over a desired band of tuning.</p> |
