200 



BELL SYSTEM TECHNICAL JOURNAL 



to approximately 73 ohms the mismatch did not exceed 4 to 1 which 

 gave less than one decibel added loss over impedance matching.'* As 

 a considerable wave-length range had to be covered, a single wave- 

 length match was of no utility. An open-wire line of less than 250 



Fig. lb — Rear view of measuring set with shielding covers removed. 



ohms impedance is not easy to construct. A thermocouple was 

 located at the antenna connection, and the resulting direct current was 

 fed down the transmission line and filtered out by a choke coil — con- 



4 Sterba and Feldman, Proc. L R. E., vol. 20, p. 1103, Fig. 12; July (10.^2). Bell 

 Sys. Tech. Jour., July. 1932. 



