APPLICATIONS OF THE CYLINDRICAL ARRAY 



Cylindrical-array antennas have been used extensively for beacons, 

 TACAN, and other applications where omnidirectional antenna radiation patterns 

 are required. When the omnidirectional pattern was desired, only the constant 

 mode was excited in each ring of elements. However, if a directional beam is 

 desired, all efficient modes must be used. The computation of these modes, or of 

 the related excitation coefficients, is accomplished by means of a high-speed 

 computer. Some of the results of the computation will be discussed later. 



The methods of exciting the elements of the configuration vary for the par- 

 ticular application, but for scanning a pencil beam, several techniques have been 

 proposed: 



1. The matrix method, which uses a group of matrices to excite the various 

 modes. The beam can be steered by summing the individual modes. 



2. The "Wullenweber" method, using a mechanical switching technique to 

 move the beam through 360° in azimuth. 



3. The lens-switch technique previously discussed, i.e., CARAMBA I. 



4. The use of individual amplitude and phase distribution at each element as 

 previously discussed, i.e., CARAMBA II. 



Consider a cylindrical array consisting of a lens feeding a ring of vertical 

 linear arrays as elements, where each element of the linear array is made up of 

 the radiating element and either a digital phasor board or a true-time-delay board 

 to apply the proper phase for elevation scanning. Essentially, this arrangement is 

 a combination of items 3 and 4 above or of item 3 and the SAMB techniques. There 

 is some redundancy because of the lens and the independent phase and amplitude 

 control at the elements. However, the lens is a practical power divider, providing 

 a convenient method of implementing 360° azimuth scanning, and in combination 

 with the digital phasor boards gives a highly versatile research tool for studying 

 the feasibility and limitations of cylindrical elevation scanning of pencil beams. 

 Many of the components developed for CARAMBA I and II can be directly used in 

 the proposed cylindrical array. In addition, other properties of the array can be 

 investigated experimentally, i.e., monopulse, multifrequency, and multi- 

 function techniques. 



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