A Wideband Cavity-Slotted Waveguide Antenna for mm-Wave Automotive Radar Sensors

A wideband cavity-slotted waveguide antenna is proposed for millimeter-wave (mm-wave) automotive radar applications. The antenna consists of a rectangular waveguide cavity with four rectangular slots. A TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">150</sub> mode and a TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">160</sub> mode are excited in the rectangular cavity. A combination of the TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">150</sub> mode and the TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">160</sub> mode leads to a wideband operation. A radiating layer is introduced above the slotted waveguide cavity to improve the impedance matching and the radiation patterns. The cavity-slotted waveguide antenna is fed by a rectangular waveguide at the bottom center of the cavity for avoiding the main beam squinting. Simulation and measurement results show that the cavity-slotted waveguide antenna achieves a wide bandwidth of 69 GHz to 91 GHz with an antenna gain of 14.5 dBi. A 6-TX/8-RX antenna module is developed to demonstrate the potential for commercial automotive radar sensors. Stable fan-beam radiation patterns and antenna gains are obtained.