An Omnidirectional Radial Parallel-Plate Waveguide Antenna Using Wideband Mode Converters

Two wideband millimeter-wave antenna structures are presented, which provide linear vertically, respectively, horizontally polarized omnidirectional radiation fields. Both antennas are realized in hollow waveguide technology and operate throughout the entire band of the feeding rectangular hollow waveguide. The measurement results of a manufactured prototype for vertically polarized radiated fields for the frequency range from 75 to 110 GHz ( W -band) show good agreement with simulated data and meet the specifications with regard to low return loss and vertically polarized omnidirectional radiation. Due to the scalability of the antenna structures, their geometry can easily be adapted for other frequency bands.