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BELL SYSTEM TECHNICAL JOURNAL 



circuit. The adjustable duplexing transmission lines may be seen in the 

 side compartment of the Main Unit on Fig. 9. 



The equipment just described could be operated over a small frequency 

 band of about 40 megacycles in the neighborhood of either 700 or 500 meg- 

 acycles. The transmitter, receiver, and duplexing circuits were tunable 

 over the entire range, but it was necessary to set up the antenna for one 

 band or the other. This was accomphshed by installing the proper one of 

 the two sets of dipoles furnished, and installing or omitting a set of wedges 



Fisr. 14— CXAS— High voltaKC rectifier 



which tilted the reflector wings to change the parabola focal length. This 

 antenna set a precedent in design in that the dipoles and coaxial harness 

 were designed for fairly broadband operation and were entirely free from 

 field tuning adjustments which had been very troublesome in earlier 

 equipment. 



The CXAS Radar was demonstrated to the Navy in December 1940. 

 After a few tests it was decided by the Navy to standardize on the 700- 

 megacycle band. One of the principal reasons for this was that the tests 

 had proved the superiority of shorter waves for surface target work; the 



