Millimeter-Wave Capacitively Coupled Microstrip Patch Array Antenna for 79 GHz Radar Sensors

In this paper, a novel capacitively coupled microstrip patch array antenna is proposed for 79 GHz radar sensors. The proposed antenna has advantages of low profile, low cost and ease of fabrication by implementing it on a millimeter- wave substrate. Two types of capacitively coupled patch arrays are designed and developed; one is 1 × 18 array for the short- range radar (SRR) sensor and the other is 4 × 18 array for the mid-range radar (MRR) sensor. To confirm the feasibility of the proposed antenna, the prototypes of the designed antennas are fabricated and measured. The simulated and measured reflection coefficients are in good agreement and less than -10 dB in a wide range of frequencies including 79 GHz. The measured maximum antenna gains are 13.94 dBi and 18.03 dBi for the 1 × 18 array and 4 × 18 array in the boresight direction at 79 GHz.