Non-Planar Quasi-Self-Complementary Ultra-Wideband Feed Antenna

We are presenting a novel ultra-wideband, dual polarized, antenna design based on a non-planar quasi self-complementary (QSC) approach. An important characteristic of this QSC antenna is an input match better than -10 dB over a decade of bandwidth. We have demonstrated the concept by fabricating a QSC prototype antenna that works from 400 MHz to 4.0 GHz. We have measured the prototype performance in terms of input impedance and radiation patterns, from which the antenna directivity, beamwidth, polarization, and aperture efficiency for a 65° illumination angle were calculated. From these measurements we confirmed the ultra-wideband characteristics of the QSC feed prototype. In particular, we looked for the presence of resonances by measuring the radiation patterns with 3 MHz resolution, over the decade of bandwidth, in both polarizations, and none was found. The measured directivity of the QSC antenna feed is 10 dBi. The half beam-width, at -10 dB level, varies between 60° and 70°, with a frequency average value of 65°. The measured beam-integrated cross-polarization inside the -10 dB level of the patterns is better than -10 dB. The phase center location does not move with frequency.