| 摘要 |
947,145. Electro-mechanical filters. STANDARD TELEPHONES & CABLES Ltd. Dec. 18, 1959 [Dec. 24, 1958], No. 41706/58. Heading H3U. An electromechanical filter comprises a plurality of torsional resonators 38, 40, 41, 42, 39 of dumb-bell form connected together by separate coupling necks 43, 44, 45, 46. The resonators can be less than half a wavelength long. The resonators 38 and 39 are circularly polarized magnetically and form the cores of transducer units having driving coils 36, 37. At least one of the coupling necks, e.g. 43 and 46 is in the form of a solid of revolution composed of three successive cylindrical sections of which the intermediate section is of larger diameter than either of the end sections. The resonators 40, 41 and 42 can be of " Ni-Span-C " (Registered Trade Mark) and the transducer resonators 38, 39 of a nickel-zinc ferrite. The coupling necks can be of brass having a force fit in an axial hole in the resonators. The filter is supported at the ends by pivots 47, 48 of polytetrafluorethylene which engage central bores in the resonators 38, 39. Intermediate support for the filter is provided by two annular bearings 49, 50 of polytetrafluorethylene surrounding the coupling necks 44, 45 and fixed in circular holes in brackets 33 and 34. Dimensions and electrical characteristics are stated.
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