Extensions to the theory and design of electric wave-filters

The problem of terminal wave-filter impedance characteristics is considered in this paper, in particular that of obtaining an approximately constant wave-filter impedance in the transmitting bands of a wave-filter of any class, which is of importance where the wave-filter is terminated by a Constant resistance, the usual case. The solution obtained is based upon the repealed use of the methods of deriving wave-filter structures which gave the M-types, combined with composite wave-filter principles. The results are wave-filter transducers which at one end have standard “constant k” image impedances and at the other have image impedances which can theoretically be made constant in the transmitting bands to any degree of approximation desired. Practical fixed structures are shown. Parts I and II give this derivation and composition of wave-filter structures. Two allied subjects, respectively, the designs of networks which simulate the impedances of wave-filters, and of loaded lines, are dealt with in Parts III and IV, such designs making use of the previous results. The four Appendices contain new reactance and wave-filter frequency theorems, particular fixed transducer designs and certain equivalents; also, a chart for determining terminal losses at the junction of such a fixed wave-filter transducer and a resistance termination. This chart supplements those previously given in a chart method of calculating wave-filter transmission losses.