An All‐Metal Slotted Waveguide Antenna for 79 GHz Automotive Radar Applications

ABSTRACT An all‐metal slotted waveguide antenna is proposed for 79 GHz millimeter‐wave automotive radar applications. The slotted waveguide antenna consists of a jagged rectangular waveguide cavity with four rectangular slots which forms a linear array. A TE mode is excited in the rectangular cavity by a rectangular waveguide feed at the bottom center of the cavity. Four radiating slots are introduced above the jagged cavity to enhance the radiation of the slotted cavity, thus improving the impedance matching and increasing the antenna gain. Simulation and measurement results show that the all‐metal slotted waveguide antenna achieves a peak gain of 14 dBi with a fan‐beam radiation pattern and an impedance bandwidth of 7%, covering the 79 GHz band (76–81 GHz) for global automotive radar sensors. A two‐transmit/two‐receive (2‐TX/2‐RX) antenna module is investigated. The isolations between TX antennas and between RX antennas are higher than 30 dB. A 6‐TX/8‐RX antenna module is developed to demonstrate the potential for commercial automotive radar sensors. Stable radiation patterns and antenna gains are obtained for all of the TX/RX antennas, suitable for automotive radar applications.