A wideband millimeter wave CP antenna by using tapered dielectic polarizer

This paper presents a circularly polarized millimeter wave antenna by using a tapered polarizer. The polarizer consists of several air and dielectric slabs, which can be used to switch the polarization of the antenna from linear polarization into circularly polarization. Besides, with the tapered shaped, the polarizer can decrease the sidelobe of the radiation pattern and increase the gain of the antenna. For demonstration, a millimeter wave antenna with the proposed polarizer is implemented and measured. The proposed antenna with the polarizer achieves a wide impedance bandwidth of 50% from 45 to 75 GHz for the reflection coefficient ≤ -10 dB, and yields an overlapped axial ratio bandwidth of 26% from 50 to 65 GHz for the axial ratio ≤ 3 dB. The maximum gain of the antenna reaches to 17 dBic. The proposed methodology of this design can apply to applications related to millimeter-wave wireless communication systems. The ultimate goal of this work is to develop a wideband, high-gain and low-cost antenna for the millimeter-wave frequency band, which is a good candidate for 5G communication.