Vertically Polarized Omnidirectional Reflector Antenna Fed by a Circular Waveguide Bent TM01 Mode Converter for the 150 GHz Band

A vertically polarized horizontal-plane omnidirectional antenna with a circular waveguide bent $\text{TM}_{01}$ mode converter and an axisymmetric single reflector is designed and fabricated for the 150 GHz band. Determining a frequency range of 147.8 GHz to 170.0 GHz as the operational band, where the transmission coefficient ratio of the $\text{TE}_{11}$ mode to the $\text{TM}_{01}$ mode is less than 1/3 that in the designed mode converter, the realized gain is 2.2 dBi to 8.8 dBi, and the angular gain variation at the measured frequencies in the band is 4.9 dB at the maximum in the fabricated antenna