AUSTIN: RESISTANCE OF ANTENNAS 9 



now commonly used, showing itself in various tests to have an 

 energy sensitiveness from three to ten times that of the electro- 

 lytic at minimum signal. The response as judged by the shunted 

 telephone method is more nearly proportional to the current than 

 to the current squared as in most other detectors. 



The cause of detector action is probably complicated. There 

 is a certain amount of true rectification as shown by a galva- 

 nometer connected in place of the telephone. This is not, however, 

 always in the same direction, and the galvanometer sensitiveness 

 is much less than that of the telephone. It is quite possible that 

 the sense of the rectification changes from instant to instant and 

 the galvanometer deflection represents merely the residual in 

 one direction or the other. In addition to the rectifying effects 

 it is probably that the changing contact gives rise to an action 

 similar to that of the Poulser ticker. 



RADIO-TELEGRAPHY. — A preliminary note on the resistance 

 of radio-telegraphic antennas. L. W. Austin. U. S. Naval 

 Wireless Telegraphic Laboratory. 



In the Physikalische Zeitschrift for April 15, C. Fischer published 

 an article on the determination of antenna resistance. His 

 method, in brief, is the substitution of an air condenser in place 

 of the antenna and ground keeping the inductance common to 

 both circuits and introducing resistance in the condenser circuit 

 until the current becomes the same as that when the antenna and 

 ground were used. This method, though I am not aware that it 

 has ever before been published, has been in use in America for 

 the measurement of antenna resistance since 1905 or 1906 and was 

 I believe first suggested by R. A. Fessenden. 



It has been known in a general way to many experimenters 

 that the antenna resistance was larger at the longer wave lengths 

 than should have been the case according to the Herzian theory of 

 radiation. 



In his article Dr. Fischer has given very interesting experi- 

 mental observations and curves showing that this increase in 

 antenna resistance is under certain circumstances proportional 



