The Bell System Technical Journal 



Devoted to the Scientific and Engineering Aspects 

 of Electrical Communication 



EDITORIAL BOARD 



J. J. Carty Bancroft Gherardi F. B. Jewett 



E. B. Craft L. F. Morehouse O. B. Blackwell 



H. P. Charlesworth E. H. Colpitts 



R. W. King-Editor 



Published quarterly by the American Telephone and Telegraph Company, 



through its Information Department, in behalf of the Western Electric 



Company and the Associated Companies of the Bell System 



Address all correspondence to the Editor 

 Information Department 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



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50c. Per Copy Copyright. 1923. $1.50 Per Year 



Vol. II JANUARY, 1923 No. 1 



Theory and Design of Uniform and Composite 

 Electric Wave- filters 



By OTTO J. ZOBEL 



THE electric wave-tilter, as regards its general transmission 

 characteristics and its extremely important role in communica- 

 tion systems, is well known. Its physical theory was discussed in 

 detail in the preceding number of this Journal by its inventor, G. A. 

 Campbell. In the present paper it is proposed to present systematic 

 general methods of wave-filter design, together with representative 

 designs, which have been developed in connection with the practical 

 utilization of this device in the plant of the Bell System. 



First is considered a general theory of design combining physical 

 and analytical considerations which gives explicitly the structure 

 of a uniform type of wave-filter having any preassigned transmitting 

 and attenuating bands as well as desirable impedance and quite 

 arbitrary attenuation characteristics. Next, this theory is applied 

 to the design of a low-and-band pass wave-filter from which are 

 derived design formulae for all the practical uniform wave-filter struc- 

 tures in present use, belonging to the classes low pass, high pass, 

 low-and-high pass, and band pass. Then the subject of composite 

 wave-filters is taken up, these being non-uniform wave-filter networks 



