416 BELL SYSTEM TECHNICAL JOURNAL 



the simulating and the compensating^ networlcs for loaded lines 

 devised by the writer at \arioiis times within about the last tweKe 

 years. Of course, the impedance of any loaded line could be simulated, 

 as closely as desired, by means of an artificial model constructed of 

 many short sections each having lumped constants; but such structures 

 would be very expensive and very cumbersome. Compared with 

 them the networks described in this paper are very simple non-periodic 

 structures that are relatively ine\pensi\e and are quite compact: 

 yet the most precise of them ha\e pro\ed to be adequate for simulating 

 with high precision the characteristic impedance of any periodically 

 loaded line, while even the least precise (which arc the simplest) 

 suffice for a good many applications. The compensating networks 

 also are of simple form. Design-formulas are included for all of the 

 networks depicted; and certain supplementary design-methods are 

 indicated. Finally, a considerable number of i)rartical a])i)lications 

 are outlined (Part \'III). 



I'.XKr I 



lMI'ltI).\N( !•; OI'" L()AI)i:i) I.IN'ICS — GIvNICKAI, t"oNSll)i:UA 1 IIINS 



Before jiroceeding to the more precise and detailed treatment of 

 the impedance of periodically loaded lines in Parts II and III, it 

 seems desirable to furnish a background liy outlining broadly the 

 salient facts. For this purpose the loaded line will be comjxired with 

 its "corresponding smooth line," that is, the smooth line having the 

 same total constants (inductance, capacity, resistance, leakance). 



Comparison icith the Correspondin" Smooth Line 



At sulhcientK' low fre(|uencies the impedance of a periodicalK' 

 loaded line approximates to that of the corresponding smooth line; ' 

 but at higher frecjucncies departs wideh'. Moreo\'cr, the impedance 

 of the loaded line depends very much on its relative termination — 

 fractional end-section or end-load ("load" is here used with the same 

 meaning as "load coil" or "loading coil"). 



To bring out simply and .sharply the contrast between a periodicalh- 

 loaded line and the corresponding smooth line, the effects of dissipa- 

 tion will at first be ignored, although the contrast is somewhat height- 

 eneci thereby. 



It will be recalled tli.il the .il lemi.il inn cimst.inl. the |)iiase velocity, 

 and the characteristic impedance of a n(in-dissi]).iii\e smooth line are 



' Defined in the second paragraph of I'.iii l\ . 



