CROSSTALK BETWEEN COAXIAL TFLiNSMISSION LINES 161 



Both coaxial circuits were terminated in resistances closely equal to 

 the absolute values of their characteristic impedances. The termi- 

 nations were carefully shielded to prevent any crosstalk at these points. 

 Careful shielding and grounding were found necessary to reduce errors 

 due to longitudinal currents, unbalances, and interference between 

 different parts of the measuring circuit. The overall accuracy of 

 the measuring circuit attained was better than .5 db when the difference 

 in input to output levels amounted to 150 db. 



Agreement between Theory and Experiments 



The general agreement between the theory and the experiments is 

 indicated by the curves in Fig. 5 and Fig. 6, which give the crosstalk 

 values for cases of two small coaxial pairs with solid outer shells in 



Q 120 



20 25 30 35 40 45 50 

 FREQUENCY IN KILOCYCLES PER SECOND 



Fig- 5 — Crosstalk between two coaxial pairs 20 ft. long using refrigerator pipe 

 .032 inch thick for outer conductors. Both coaxial pairs terminated in 70 ohms. 

 Outer conductors in contact. 



u no 



60 80 100 120 



FREQUENCY IN KILOCYCLES PER SECOND 



Fig. 6 — Crosstalk between two coaxial pairs 25 ft. long. Outer conductor made 

 of copper .008 inch thick, .232 inch inner diameter. Both coaxial pairs terminated 

 in 40 ohms. Outer conductors in contact. 



