COUPLED WAVE THEORY AND WAVEGUIDE APPLICATIONS 



GG7 



tion for large Qj-w values at the expense of an increased S/tt value for the 

 first discrimination peak. 



The first two lines of Fig. 4 gi^•e the discrimination functions for two 

 forms of cosine taper; Fig. 5 shows a plot of the first function and Fig. G 

 shows a plot of the second function for a particular case. These figures 

 illustrate the importance of the slope at the ends of the coupling distri- 

 bution. Comparing Fig. 5 with Fig. 3, Fig. 5 has a larger end-slope, shows 

 a lower value of Q/-k for the first peak in discrimination, but provides 



FIGURE FOR 

 DISCRIMINATION 



DEFINITION 



95(X)=COs(j^) 



S(X) 



SHAPE 

 A 



DISCRIMINATION 



COS e 



95(X) = i+||i+cos(^)[ 



2 



■f) 



SIN e Ck SIN (kg) 



^-o)Vm 



f95(x) = l + C 



L"_kL 

 Z 2 



2 2 



(i+ck) 



SIN e ^rk siN(ke) 

 9 * (ke) 



rs^(x)=i 



!^<lxi<^ 



ii(X) = Hc4(i|=+x) 



-'^<X<0 

 2 



kL 



2 



Fig. 4 — Discrimination functions corresponding to certain coupling distribu- 

 tions. 



