A 2–5 GHz circular Eleven antenna with improved BOR1 efficiency

This paper presents an improved Eleven antenna - the circular Eleven antenna, which has 0.3 dB higher BOR
₁
efficiency than previous models. In this way the aperture efficiency becomes higher when it is used as a feed for reflector antennas. The new feed is constructed by using circularly curved folded dipoles which are printed on four flat circuit boards, referred to as then petals as in previous models. The demonstration of the improvement is shown over the limited frequency range 2 - 5 GHz to reduce computation time.