AUSTIN: HIGH FREQUENCY RESISTANCE 



113 



I have, therefore, from data given by Professor Zenneck* 

 graphically computed the sizes of wire which may be used at 

 various wave lengths without causing the difference in direct 

 and high frequency resistance to exceed 1 per cent. Doubling 

 the diameter given in the table will produce a difference between 

 direct and high frequency resistance of approximately 10 per 

 cent, while one-half the diameter given in the table will reduce 

 the difference to approximately ^ percent, (Zenneck). The val- 

 ues are given for copper and platinum as well as the high resist- 

 ance materials constantan and manganin. Advance wire is 

 practically identical electrically with constantan, while for high 

 resistance German silver the values are nearly the same as for 

 manganin. 



TABLE OF WIRE SIZES 



For Which the High Frequency Resistance Will be Less Than 1 Per Cent 

 Greater Than Direct Current Resistance 



The column of the table under Maximum Current gives the 

 approximate current which may be carried by the various sizes 

 of constantan wire without undue heating. The current capacity 

 of the manganin is very nearly the same. 



1 Zenneck, Leitfaden der drahtlosen Telegraphie, p. 352. 



