Ultra-Wideband Electromagnetic-Polarization Filter Applications to Conventional Horn Antennas for Substantial Cross-Polarization Level Reductions

This paper addresses the difficulties of achieving lower cross-polarization EM field transmission (or reception) levels by employing wideband electromagnetic-polarization filters (EMPFs). These electromagnetic-polarization filters are applied as add-on screens to reduce the cross-polarization levels of standard-gain horns (SGHs) and diagonal horns (DH). Cross-polarization level reductions as much as 19 dB are presented for diagonal horns with add-on screens. Similarly, more than 9 dB cross-polarization reductions are shown for standard-gain horns across the operational bandwidth. An alteration was made to the add-on screens by making use of Ludwig's third coordinate definition. This modification resulted in further cross-polarization suppression in the vicinity of the boresight direction. For instance, for an X-band standard-gain horn, near the boresight angular region where the cross-polarization level was kept below -60 dB, this increased by 26% with the use of this modified add-on screen.