INTRODUCTION 



In the continuing effort to develop shipborne radar systems capable of 

 meeting military needs, important objectives have been broad-spectrum signals, 

 low-side-lobe antennas, and bearing agility independent of frequency. Integration 

 of electronic systems (as in the use of the same antenna structure for several 

 functions and at various frequencies) has been stressed, to reduce space, weight, 

 and manning. Previous studies have shown that the antenna of the circular-array 

 type for a single ring of elements is both effective and feasible in meeting these 

 objectives. A natural outcome of the wide-spectrum ring-array development was 

 the use of a linear array as an element for a cylindrical array (fig. 1). 



Reference 1 (see list at end of report) describes the preliminary feasibility 

 investigation of the ring-array concept, presents design parameters for cylinder- 

 backed ring and arc configurations, and establishes three areas for continuing 

 investigation. The second, and part of the third, of the recommended study areas 

 have been completed and are reported in references 2-4. Briefly, the work included 

 theoretical studies and computations relating ring-array current distributions to 

 array radiation patterns; formulation of beamwidth and amplitude and phase distribu- 

 tion for use in designing narrowbeam, low-side-lobe, circular-array antennas; and 

 design and test of a 128-element ring-array antenna, using an R-2R parallel-plate 

 lens feed system, with beam position electronically steerable in discrete steps. 

 Another phase of the third study recommended had to do with power dividing and 

 phasing techniques and the possibility of combining linear and circular array tech- 

 niques for use in two coordinate azimuthly symmetrical arrays. The work to be 

 reported here was performed as part of that study and, in particular, is concerned 

 with methods of beam-forming to obtain pencil beams from a cylindrical configura- 

 tion of elements. 



