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BELL SYSTEM TECHNICAL JOURNAL 



The shape of the phase curves will depend on the relative rates of varia- 

 tion of Bt and Bl with frequency. Assuming the linear variations with fre- 

 quency of (4.46) and (4.47) the shapes can be computed. This has been done 

 for Cl/Ct = 1, 3, 10 and the results are shown in Fig. 4.17. 



Fig. 4.17 — Phase shift per section, Q, vs radian frequency w for the conditions of Fig. 4.16. 



Fig. 4.18 — Longitudinal and transverse susceptances which give — tt radians phase 

 shift at the lower cutoff (co = col) and degrees phase shift at the upper cutoff (w = cor). 

 This means a negative phase velocity. 



It is of course possible to make oj/, > cor • In this case the situation is as 

 shown in Mg. 4.18, the pass band extending from co/, to cot . At co — wl , 

 cos B = —\, 6 = —IT. At CO = cor , cos 0=1 and 6 — O.ln Fig. 4.19, as- 

 suming (4.46) and (4.47), has been plotted vs co for CJCt = 1, 3, 10. 



The curves of Figs. 4.17 and 4.18 are not exact for any physical structure 

 of the type shown in Fig. 4.10. Tn lumped circuit terms, they neglect coupling 



