POLYROD ANTENNAS 



845 



conical-cylindrical design of Fig. 8, but which is longer and is tapered for 

 slightly less than half its length. The minor lobes (solid curve) are all lower 

 than 0.125, a marked improvement over Fig. 8. From the measured gain, 

 A is 1.82. 



Regardless of whether the cross-section is^square, rectangular, or round, 

 radiation is nearly isotropic about the axis of^the polyrod. For the patterns 



-;o 1.0 

 < _i 



a. > 

 Ouj 

 2JJ0.9 



I 

 Q. 



0.8 



0.6 



0.5 



1.5 2.0 2.5 3.0 3.5 4.0 4.5 



DISTANCE FROM FEED, I , IN WAVELENGTHS 



-10 10 



DEGREES OFF AXIS 



Fig. 7 — Data on a 6X tapered rectangular polyrod. 



in Fig. 6-9, beam widths in degrees between half -power points correspond 

 to values of B in (3) between about 50 and 60. 



The characteristics of polyrods can thus be correlated with array theory 

 for isotropic radiators continuously distributed along an axis. There are, 

 to be sure, minor discrepancies which might become more serious in a dif- 

 ferent range of polyrod proportions. For the lengths and cross-sections 

 tested, however, equations (1) to (5) describe polyrod performance very 

 satisfactorily for engineering purposes. 



