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BELL SYSTEM TECHNICAL JOURNAL 



lens needs to correct the phase by more than one wavelength. It follows 

 that no portion of the lens need to be thicker than X/(l — A^). 



(0) 

 FEED FEED 



Fig. 30 — Comparison of Dielectric and Metal Plate Lenses. 



(b) 



[{l|||i|||M||||l ""i>i|{|||||l||||l 



(0) (b) 



FEED FEED 



Fig. 31 — Comparison of Unzoncd and Zoned Metal Plate Lenses. 



A cross section of a ty])ical metal j)hite lens before and after zoning is 

 illustrated in Fig. 31. This figure shows clearly why zoning reduces con- 

 siderably the size and mass of a lens. 



