| 摘要 |
463,006. Impedance networks. GENERAL ELECTRIC CO., Ltd., and ASPIN, J. J. E. Jan. 20, 1936, No. 1809. [Class 40 (iii)] A band-pass filter, suitable for excluding the intermediate frequency from circuits in a superheterodyne receiver, comprises two tuned circuits A, B coupled by one or more T-sections Z1, Z2, Z3, which are equivalent to a coupling condenser whose capacity diminishes as the frequency rises. Preferably, the series arms Z1, Z2 are condensers while the shunt arm Z3 is a rejector circuit, Fig. 3 (not shown), or an acceptor circuit, Fig. 4 (not shown), according as the intermediate frequency is lower or higher than the signal frequency of the superheterodyne receiver. In the former case the resonance frequency of the arm Z3 lies below, and in the latter above, the signal-frequency range. Specification 391,598 is referred to.
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