laminatp:d traxsmissiox lines. I 



989 





-0.08 -0.06 -0.04 -0.02 



0.08 0.10 



Fig. 9 — Xormalized stack resistance Re g\h\K\ versus dielectric inisniatch 

 l)arameter fc, for different values of i\lh\. 



raising the dielectric constant and thus lowei'ing the impedance of the 

 main dielectric, then since the attenuation constant of the line is pro- 

 portional to the ratio of stack resistance to dielectric impedance, we 

 must have Re ^i5i/vi considerably smaller than unity to obtain a lower 

 attenuation with the Clogston line than with an ordinary air-filled line 

 having solid metal walls. 



For a plane Clogston 1 line with stacks of ecjual thickness, the frac- 

 tional change in the atteimation constant with freciuency is equal to 

 the fractional change in the resistance of either stack, whether this 

 change ari.ses from the effects of finite lamina thickness or from di- 

 electric mismatch or both. The fractional change in the attenuation con- 

 stant of a coaxial Clogston 1 depends not only on the change in resist- 

 ance of each stack, but also on the geometric proportions of the cable, 

 in the manner expressed by e(iuation (200) of Section V. 



The effect of dielectric mismatch on the overall attenuation versus 

 frecjuency characteristic of a Clogston cal)le is in general to reduce the 

 total frequency range (in Mc-sec~') over which the Clogston cable has 

 a smaller attenuation constant than a conventional air-filled coaxial 

 cable of the same size. To calculate the lower crossover frequency we 

 may ordinarily neglect finite lamina thickness effects and use equation 

 (241) for the stack impedances, while at the upper crossover freciuency 

 the stack impedances are very nearly e(|ual to A'l , as given l)y (217). 



