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BELL SYSTEM TECHNICAL JOURNAL 



reduced. By re(lucin<f these minor lobes to a low value, the region around 

 the main beam is free of lobes, thus greatly reducing the possibility of false 

 tracking due to "cross overs" between the main beam and the minor lobes. 



14.8 The Polyrod Fire Control Antenna 



The Polyrod Fire Control antenna is an arra}' scanner emplo}ing essen- 

 tially the same principles as those used in the multii)le unitsteerable antenna 



Fig. 50 — Mark 4 Radar Antenna on Ikittleship Tennessee. 



system (MUSA) developed before the war for short-wave transatlantic 

 telephony. Some of these principles have been discussed in Sec. 12.2. 

 That they could be applied with such success in the microwave region was 

 due to a firm grounding in waveguide techniques, to the invention of the 

 polyrod antenna and the rotary phase changer, and especially to excellent 

 technical work on the part of research, development and production person- 

 nel. It is perhaps one of the most remarkable achievements of wartimq 



