670 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1954 



60 



Fig. 8 — Discrimination versus B/v for a linear taper and uniform coupling 

 superposed. 



and letting 



/^T- = i^l + /^2+ •••i^n, 



(9) 



the discrimination function for the composite couphng distribution 

 ^t{x) is given by 



Discrimination 



Ft{Q = 0) 



Ft 



(10) 



Another useful theoretical approach to the employment of multiple 

 distributed coupling functions is illustrated in Fig. 9. The top sketch 

 represents any coupling function <^i(a;). The lower sketch shows a new 

 coupling function </>2(^) formed by locating a 4>iix) at ±d/2 on the "x" 

 axis. Using F\ to denote the transform for <\>\{_x), and Fi to denote the 

 transform corresponding to 02(a;), 



wherein 



Fa = 2iPi cos Q', 



''-a -a 



(11) 



