Wideband Circularly Polarized Horn Antenna With Twisted Ridges of Gielis Super-Formula Contour

This communication presents a wideband singly fed circularly polarized (CP) twisted-ridge horn antenna. This horn antenna has a record-high CP operating bandwidth of 86.3%. The Gielis super formula is used to design the twisted ridges, enhancing the axial ratio (AR) bandwidth. A new waveguide-coax launcher with a ridged back cover is incorporated to boost the impedance bandwidth. Using these new design techniques, the overlapped bandwidth of the CP horn antenna can be increased. For demonstration, a K-band CP twisted-ridge horn antenna is designed, fabricated, and experimentally evaluated. The measured 10-dB impedance bandwidth and 3-dB AR bandwidth are 90.6% (14.6–38.8 GHz) and 88.2% (15.4–39.7 GHz), respectively, giving a very wide overlapped bandwidth of 86.3% (15.4–38.8 GHz). It is found that the measured antenna gain generally increases with frequency in the operating passband.