Low-profile ultra-wideband directional dipole antenna as a feed for reflectors in radio telescopes

In this paper, a small top plate is found useful to improve the impedance bandwidth of an ultra-wideband dipole antenna horizontally above a ground plane. A linearly-polarized prototype based on this new and simple design methodology can operate over nearly 3.5∶1 bandwidth with return losses better than 10 dB, and with nearly stable radiation patterns, high BOR 1 efficiency and aperture efficiency over the entire operating band.