Circularly Polarized Excitation for the Silver/ Polypropylene Hollow Waveguide

A millimeter-wave (mm-wave) circularly polarized excitation for the silver/polypropylene (Ag/PP) hollow waveguide is proposed in this manuscript. The excitation consists of a WR-15 waveguide to substrate integrated waveguide (SIW) transition, a section of SIW, and an end-fire circularly polarized antenna structure. Circular polarization propagation is realized, avoiding high order modes and polarization mismatch problems. The circularly polarized excitation performs well in the 52.2-63.4 GHz band, indicating a fractional bandwidth of 19.4%. This design offers a solution for the waveguide integrated with planar circuits in the mm-wave band.