An antenna array (10) comprises a plurality of antenna elements (20-32)
creating a plurality of radio frequency waves. The central portion (185)
of opposed edges of the waves are guided with conductive material. The
waves are isolated from each other by non-conductive (cir or dielectric)
spaces (189). The waves are guided by tapered surfaces (140, 141) having a
predetermined thickness and emitted through a mouth having a mouth length
(M). The ratio of the predetermined thickness to the mouth length is
increased until there is no substantial increase in the high frequency
limit of the array.
