Broadband Circularly Polarized Dielectric Rod Antenna for Millimeter-wave Communications

This paper presents a method to achieve broadband 3-dB Axial Ratio bandwidth (ARBW) in circularly polarized (CP) dielectric rod antenna from a linearly polarized (LP) waveguide. The proposed antenna achieves an impedance bandwidth covering the whole Ka band and an overlapped 3-dB ARBW of 37% (27.5 to 40 GHz). It consists of a feed taper and a rotated body taper. Circular polarization is achieved by the rotation of the body taper, which prompts the LP incident wave from the waveguide to disassemble into two orthogonal electric fields with small magnitude disparity. 90° phase difference is achieved by adjusting the length and the dimension of the rectangular cross-section of the body taper. This antenna is simple, easy fabricated and wideband.