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BELL SYSTEM TECHNICAL JOURNAL 



per unit of length. The first term of (1) represents the losses in the 

 conductors, while the second term represents those in the dielectric. 



When the dielectric losses are small, the attenuation of a coaxial 

 circuit increases, due to skin effect in the conductors, about in accord- 

 ance with the square root of the frequency. With a fixed diameter 

 ratio, the attenuation varies inversely with the diameter of the circuit. 

 By combining these relations there are obtained the laws of variation 

 of band width in accordance with the repeater spacing and the size of 

 circuit, as stated previously. 



The attenuation-frequency characteristic of the flexible structure 

 illustrated in Fig. 2, with about .3 inch diameter, is given in Fig. 6. 



5 6 



200 400 600 800 1000 1200 1400 1600 I8( 



FREQUENCY IN KILOCYCLES PER SECOND 



Fig. 6 — Attenuation of small flexible coaxial structure (Fig. 2). 



The figure shows also that the conductance loss due to the insulation 

 is a small part of the total. 



It is interesting to compare the curves of the transmission character- 

 istics of the coaxial circuit with those of other types of circuits. Figure 



