Slant-Polarized Coaxial Slot Antenna Using Gap Waveguide MLW Technology for Automotive Radars
Authors:
Reza Gheybi Zarnagh, Abolfazl Haddadi, Andres Alayón Glazunov
Abstract:
This paper presents the design of a coaxial slot antenna utilizing gap waveguide (GW) multilayer waveguide
(MLW) technology for automotive radar applications. The antenna employs a low-loss, air-filled coaxial
transmission line, formed by stacking three distinct metal sheets. Its primary antenna element is a side-fed
column featuring eight in-line slant slots, each pair excited via a coupling slot and intermediate cavity. To
minimize leakage caused by small air gaps between the metal sheets, an electromagnetic bandgap (EBG)
structure is incorporated along the transmission lines. The antenna supports dedicated transmit and receive
channels for a multiple-input multiple-output (MIMO) automotive radar system. A five-layer structure
progressively rotates the electric field orientation by 45° through intermediate cavities, enabling the slant
polarization. The design achieves an impedance bandwidth of |S11| < −10 dB across the 76–81 GHz band
allocated for automotive radar. With eight radiating slots, the antenna produces a peak gain of 13.7 dBi
at 77 GHz.
