Dual-Polarized Low-Profile Millimeter-Wave Slot Antenna Array Using Substrate-Integrated Coaxial Line for Vehicular Wireless Applications

In this article, a 1 × 8 dual-polarized low-profile slot antenna array with broadside radiation is proposed by exploring substrate-integrated coaxial line (SICL) for vehicular wireless applications. The proposed antenna element comprises a bowtie dipole enclosed in a cavity, with a square radiating slot etched on it. Specifically, one arm of the dipole is connected to the inner conductor of SICL, and the other is grounded by a via of the waveguide side wall. When SICL operates at quasi-TEM and TE₁₀ mode, the dipole and the waveguide can excite the TE₁₂₀ mode and TE₂₁₀ mode of the cavity for vertical and horizontal polarization with high isolation, respectively. To validate the concept, a prototype is fabricated and experimentally tested. The measured results agree well with the simulations, demonstrating that the proposed antenna array achieves an overlapped−10-dB bandwidth of 25.8–27.4 GHz, a high-isolation level over 20 dB, and a maximum gain of 14.7 and 12.7 dBi for port 1 and port 2, respectively.With the merits of simple feeding, low profile, and structural reuse, the proposed method has promising usage in large-scale dual-polarized high-gain vehicular millimeter-wave wireless applications.