Development of three models of the eleven antenna: A new decade bandwidth high performance feed for reflectors

The Eleven antenna is a novel dual polarized ultra wide band (UWB) feed with a decade bandwidth for use in both single and dual reflector antennas. The special name is associated with its basic 11 iquest configuration of two parallel dipoles with 0.5 wavelengths spacing, and because it can be used over more than a decade bandwidth (and 11 > 10 iquest) with 11 dBi iquest directivity by making the dipoles log-periodic. The phase center has a constant location in the ground plane, so a high aperture efficiency of the reflector of 66% or better is available over the whole band. The return loss is better than 5 dB, but we believe that it is possible to achieve 11 dB iquest. The feed has no balun as it is intended to be used with an active 180 deg balun and receiver. The Eleven antenna is about 11 times smaller iquest than alternative end-fire log-periodic feeds.