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BELL SYSTEM TECHNICAL JOURNAL 



spaced within the range of z (Fig. 17B). In Fig. 16, n — 6; Curve A repre- 

 sents an array with nulls distributed evenly on the complete circle and 

 Curve B represents an array with nulls evenly spaced in the range of z. 





I I I 6 SIN 



[z-e~)(z-e"~»^) (Z+ I) I 



(i-e""')(i-e"''') 



00° 120° 



Fig. 13 — Directive properties of 2 six-element arraj-s with { = X/4. Curve (A) refers to 

 a uniform array and Curve (B) refers to an array with its nulls equispaced in 

 the range of z. 



(A) 



(B) 



Fig. 14 — Disposition of null points for the arrays with directive characteristics as shown in 

 Fig. 13. 



If the total length of an array is kept constant but the number of ele- 

 ments is increased, the array may be made more directive; Figure 18 illus- 

 trates this point. This increase in directivity can be secured only if the null 

 points of the array are properly distributed within the range of s; in Fig. 18 



