Patch Array Antenna Using a Dual Coupled Feeding Structure for 79 GHz Automotive Radar Applications

This letter proposes a novel design for a patch array antenna using a double indirect coupled feeding structure to achieve broad matching and gain bandwidths for automotive radar applications. The proposed radar antenna consists of a microstrip line, a rounded rectangular radiator, and a waveguide feeding structure. The indirect coupled feeding mechanism is first applied to the rounded rectangular radiator, which is placed at an adjacent distance from the microstrip line. To further improve the broad matching and gain characteristics, another indirect coupled feeding structure is applied to the transition between the microstrip line and the waveguide feeding network. To verify the proposed antenna performance, including impedance matching, bore-sight gain, and the radiation pattern, the proposed antenna is measured in a compact antenna test range chamber. The results confirm that the proposed patch array antenna using a double indirect coupled feeding structure is suitable for the 79 GHz radar array.