POLYROD ANTENNAS 

 The width of the major lobe is given by 



Beam Width = 



B 



841 



(3) 



The constant B depends on /3 — p and on the manner in which beam width 

 is defined. For width in degrees between half power points, and with 

 j3 — p = 0.5 for maximum gain, B is computed from (1) to be about 60. 



/3-p 

 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 



< 1.2 



0.6 



-1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 

 xTT ADVANCED 



PHASE LAG IN RADIANS 



0.2 0.4 0.6 0.8 1.0 1.2 1.4 



RETARDED >TT 



Fig. 4 — Gain factor yl as a function of phase lag in endfire arrays. 



If a sinusoidal variation in excitation voltage along the radiator is super- 

 posed on the constant amplitude assumed for (1), we get 



I sin 7r(p cos Q — ^) , ,. . cos 7r(p cos — (3) 



r = \ a ; r- ::t + U ~ O) 



7r(p COS 0-/3) 



1 - 4(p COS 9 - ^y 



(4) 



where a is defined in Fig. 5. This figure gives patterns of a six wavelength 

 radiator according to (4) for various values of a. Here is fixed at 6.5 

 for maximum gain. Tapering symmetrically away from the center de- 

 creases the minor lobes. The gain is also decreased, but to a lesser extent. 



