VOLUME XXV JULY, 1946 no. 3 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Some Recent Contributions to Synthetic Rubber Research 



C. S. Fuller 351 



Characteristics of Vacuum Tubes for Radar Intermediate 

 Frequency Amplifiers G. T. Ford 385 



High Q Resonant Cavities for Microwave Testing 



/. G. Wilson, C. W. Schramm and J. P. Kinzer 408 



Techniques and Facilities for Microwave Radar Testing 



E. I. Green, H. J. Fisher, J. G. Ferguson 435 



Performance Characteristics of Various Carrier Telegram 

 Methods T. A. Jones and K. W. Pfleger 483 



Abstracts of Technical Articles by Bell System Authors 532 



Contributors to This Issue 537 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



504 per copy $1-^0 per Year 



