A Broadband High-Gain Microstrip Comb-line Antenna Featuring Amplitude and Phase Tuning Slots

Millimeter-wave antennas play critical roles in wireless communication and automotive radars. This paper presented a broadband and high-gain microstrip comb-line array antenna for millimeter-wave band applications. The proposed antenna comprises 18 radiating elements and two U -shaped slots cut on the feeding line. By introducing the slots to excite reflected waves, energy concentrates mainly at the middle part of the array, achieving a low sidelobe level while maintaining high-gain performance. Meanwhile, a broadened bandwidth of 68.74-80.70 $\mathbf{G H z}$ is obtained by adding tapered structures at the open end of the radiating elements. Simulation results show that the antenna’s gain reaches 16.37 dBi with a low sidelobe level of -18.70 dB at its design frequency of $79 \mathbf{~ G H z}$.