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BELL SYSTEM TECHNICAL JOURNAL 



strated the value of rapid scanning, yet the problem of producing a rapid 

 scanning higher frequency antenna of nearly equal -dimensions was a new 

 and different one. 



Several possible solutions to this problem were known. The array 

 technique applied so effectively to the polyrod antenna could have been 

 applied here also, but only at the expense of many more elements and 

 greater complexity. 



After much preliminary work it was finally concluded that a mechanically 

 scanning antenna, the "rocking horse," provided the best solution to the 

 higher frequency scanning problem. This solution is practical and relatively 

 simple. 



- DELAY EQUALIZING 

 WAVE GUIDE LENGTHS 



UNIT ANTENNAS 

 (VERTICAL POLYROD TRIDENTS) 



WAVE GUIDE 



DISTRIBUTING MANIFOLD 

 WITH ROTARY PHASE CHANGERS 

 (720° PHASE CHANGE PER REV.) 



INPUT 



Fig. 52. — Schematic Diagram of Poljrod Fire Control Antenna. 



The operation of the rocking horse is described in Sec. 12.1. It is essen- 

 tially a carefully designed and firmly built paraboloidal antenna which 

 oscillates rapidly through the scanning sector. Its oscillation is dynamically 

 balanced to eliminate undesirable vibration. 



Figure 54 is a photograph of a production model of the rocking horse 

 antenna. 



14.10 The Mark 19 Radar Aiilcmia^'^ 



In Anti-aircraft Fire Control Radar Systems for Heavy Machine Guns 

 it is necessary to em])loy a highly directive antenna and to obtain continu- 

 ous rapid comparison of the received signals on a number of beam positions 



"Sections 14.10, 14.11 and 14.12 were written by F. E. Nimmcke. 



