280 



BELL SYSTEM TECHNICAL JOURNAL 



equal conductivities of conductors and shield the optimum values are 

 9=^1= 6-8; "" ^\= -49. (59), (60) 



These values may be compared with 5.4 and .46, respectively, for the 

 pair of round conductors with circular shield. The high-frequency 

 attenuation of each shielded quad circuit with optimum design is, 



- </)^-^ 

 X (r Q 

 <0 -' 

 (T K yj 



0.6 



25 



'0.5 



2 "- 



: § 1 0.4 





0(0 — 



0.3 



V\g. 16 — Shieldedjquatl. 



2 3 4 6 6 7 8 9 10 II 12 



RATIO OF CONDUCTIVITIES (INNER TO OUTER CONDUCTOR) 



Fig. 17 — \'ariati()ii of optiiiiuin spacing ratio of shielded quad with conducti\it\' ratio. 



