. The Bell System technical journal . Electric Wave-Filter, G. A. Campbell, B. S. T. J.,.Nov., 1922; Theory- and Design of Uniform and Composite Electric Wave-Iilters,O. J. Zobel, B. S. t. J., Jan., 1923; Transient Oscillations in Electric Wave-Kilters,J. R. Carson and O. J. Zobel, B. S. T. J., July. 1923. 567 568 BELL SYSTEM TECIISICAL JOURNAL the advantage over other formulae and calculation methods of re-quiring for every alteration in a composite wave-filter only a partialrecalculation rather than a more or less complete one. In addition,by its use much of the otherwise necessarj calculati
. The Bell System technical journal . Electric Wave-Filter, G. A. Campbell, B. S. T. J.,.Nov., 1922; Theory- and Design of Uniform and Composite Electric Wave-Iilters,O. J. Zobel, B. S. t. J., Jan., 1923; Transient Oscillations in Electric Wave-Kilters,J. R. Carson and O. J. Zobel, B. S. T. J., July. 1923. 567 568 BELL SYSTEM TECIISICAL JOURNAL the advantage over other formulae and calculation methods of re-quiring for every alteration in a composite wave-filter only a partialrecalculation rather than a more or less complete one. In addition,by its use much of the otherwise necessarj calculation can be elimi-nated through the means of graphical representation. The main object of this paper is to present this chart calculationmethod of determining composite wave-filter transmission losses,giving its theory, the necessary charts, and an application of its use. Strtiditre of Wave-Filter Networks The ladder type of recurrent network having physical series andshunt impedances 2i and S2, respectively, as shown in Fig. 1, is the. Kig. 1—Ladder Type Recurrent Network one most frequently employed for wave-filters. Also any passivetransducer having two pairs of terminals can theoretically be reducedto the form of the ladder type. Hence, in what follows the laddertype terminology will be used understanding, however, that otherstructural types may also be included; for example, such as are deriv-able from the ladder type by the substitution of an equivalent trans-former with mutual impedance for T or n connected inductances,or the lattice type. The figure illustrates, from left to right, one mid-series section, one mid-half section (a dissymmetrical half sectionterminated at mid-series and mid-shimt points), and one mid-shuntsection all connected so as to give a uniform structure.^ The charac-teristic impedances of the ladder type at mid-series and at mid-shuntpoints are K\ and Ki, respectively. The majority of wave-filter networks are mil miifunn iliroii^lmuttheir length but
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