METALLIC DELAY LENSES j^, 



^!^Tflr"" ^T/'T' ''''"^ "^^'^ ''"^ '' ^"' "^^ ^^" '^t" 'hat this effect 

 causes the expected value of the index of refraction to be smaller than that 

 determined by the usual equation 



(4) 



Fig. 4 — Lattice of conducting disks arranged to form a plano-convex lens. Polystyrene 



foam sheets support the disks. 



To avoid this effect the elements should be shaped so as not to alter the 

 magnetic lines of force. This can be done by making their dimension in the 

 direction of propagation of the impressed waves negligibly small. 

 (b) Disk Array 



One accordingly arrives at the lens design shown in Fig. 4 in which the 

 spheres are replaced by copper foil disks lying in planes parallel to the 



