JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. I, OCTOBER 4, 1911. No 5. 



RADIO-TELEGRAPHY. — Condenser losses at high frequencies. 

 L. W. Austin, Naval Wireless Telegraphic Laboratory. 

 To appear in the Bulletin of the Bureau of Standards. 



The following experiments have been carried out in the wire- 

 less laboratory for the purpose of determining the equivalent 

 resistance of various types of condensers in high frequency cir- 

 cuits. 1 The method used was to observe the current in a spark 

 circuit containing the condensers under test and then substitute 

 a Fessenden compressed air condenser of approximately the same 

 capacity and add a high frequency resistance sufficient to reduce 

 the current to the same value as that observed with the other 

 condensers. It was found possible to make these resistance 

 observations with an accuracy of about 0.05 ohm. Special experi- 

 ments showed that the resistance of the compressed air condenser 

 under the given conditions was 0.25 ohm, which was probably due 

 to imperfect insulation and eddy currents in the metal case. 



Two types of copper coated Leyden jars were furnished by the 

 Wireless Specialty Apparatus Company, and one type each by the 

 Telefunken Company of America and the United Wireless Com- 

 pany. The Moscicki condensers were of their well known form 

 encased in brass tubes with the glass thickened at the edges of the 

 conducting coating and with these edges covered with an insulat- 

 ing liquid. The paper condenser was of a well known make. 



1 While the work was in progress a paper on the same subject by Professor Flem- 

 ing appeared. See Proc. Phys. Soc. of London, 23: 117. 1911. 



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