RADAR ANTENNAS 

 reduces (36) to the form 



/- (a) = - e V '^ ^ - e 



k-2 J 



Equation (45) can be evaluated with the help of Fresnel's Integrals 

 [ cos X' dX, j sin X' dX 



dX 



243 



(45) 



n 2n -2n -n 

 y 



^ _ j]_g__5iN_a 





-2n -no T[ 2T\ -2n -n o tt 2n 

 Fig. 14 — Patterns of Rectangular Apertures with Square Law Phase Variation. 



which are tabulated^, or from Cornu's Spiral which is a convenient graphical 

 representation of the Fresnel Integrals. 



Typical computed patterns for apertures with square law phase variations 

 are plotted in Fig. 14. These theoretical curves can be applied to the fol- 

 lowing important practical problems. 



(1) The pattern of an electromagnetic horn. 



■• For numerical values of Fresnel's Integrals and a plot of Cornu's Spiral see Jahnke 

 and Emde, Tables of Functions B, G, Teubner, Leipzig, 1933, or Dover Publications, New 

 York Citv, 1943, 



