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 ☺ 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 ☺) with 11 dBi ☺ 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 ☺. 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 ☺ than alternative end-fire log-periodic feeds.